diff --git a/Build/phpstan/phpstan-baseline.neon b/Build/phpstan/phpstan-baseline.neon
index 4114d9a5821d..0ad3063df1a8 100644
--- a/Build/phpstan/phpstan-baseline.neon
+++ b/Build/phpstan/phpstan-baseline.neon
@@ -2634,8 +2634,3 @@ parameters:
 			message: "#^Unreachable statement \\- code above always terminates\\.$#"
 			count: 1
 			path: ../../typo3/sysext/webhooks/Tests/Functional/WebhookExecutionTest.php
-
-		-
-			message: "#^Else branch is unreachable because previous condition is always true\\.$#"
-			count: 1
-			path: ../../typo3/sysext/workspaces/Classes/Service/GridDataService.php
diff --git a/typo3/sysext/backend/Classes/Utility/BackendUtility.php b/typo3/sysext/backend/Classes/Utility/BackendUtility.php
index d895f8185f42..7ec03406a08d 100644
--- a/typo3/sysext/backend/Classes/Utility/BackendUtility.php
+++ b/typo3/sysext/backend/Classes/Utility/BackendUtility.php
@@ -821,7 +821,7 @@ protected static function getRecordsSortedByTitle(array $fields, $table, $titleF
 
         while ($record = $res->fetchAssociative()) {
             // store the uid, because it might be unset if it's not among the requested $fields
-            $recordId = $record['uid'];
+            $recordId = (int)$record['uid'];
             $record[$titleField] = self::getRecordTitle($table, $record);
 
             // include only the requested fields in the result
diff --git a/typo3/sysext/workspaces/Classes/Command/AutoPublishCommand.php b/typo3/sysext/workspaces/Classes/Command/AutoPublishCommand.php
index b326f6476251..61650489a6e5 100644
--- a/typo3/sysext/workspaces/Classes/Command/AutoPublishCommand.php
+++ b/typo3/sysext/workspaces/Classes/Command/AutoPublishCommand.php
@@ -73,7 +73,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
                 );
 
             // Get CMD array
-            $cmd = $this->workspaceService->getCmdArrayForPublishWS($workspaceRecord['uid']);
+            $cmd = $this->workspaceService->getCmdArrayForPublishWS((int)$workspaceRecord['uid']);
             $tce = GeneralUtility::makeInstance(DataHandler::class);
             $tce->start([], $cmd);
             $tce->process_cmdmap();
diff --git a/typo3/sysext/workspaces/Classes/Controller/AjaxDispatcher.php b/typo3/sysext/workspaces/Classes/Controller/AjaxDispatcher.php
index 7a1300a3460b..2f49200701fe 100644
--- a/typo3/sysext/workspaces/Classes/Controller/AjaxDispatcher.php
+++ b/typo3/sysext/workspaces/Classes/Controller/AjaxDispatcher.php
@@ -33,10 +33,7 @@
  */
 class AjaxDispatcher
 {
-    /**
-     * @var array
-     */
-    protected $classMap = [
+    protected array $classMap = [
         'RemoteServer' => RemoteServer::class,
         'MassActions' => MassActionHandler::class,
         'Actions' => ActionHandler::class,
diff --git a/typo3/sysext/workspaces/Classes/Controller/Remote/ActionHandler.php b/typo3/sysext/workspaces/Classes/Controller/Remote/ActionHandler.php
index dc32f4ac1410..9307fd22c995 100644
--- a/typo3/sysext/workspaces/Classes/Controller/Remote/ActionHandler.php
+++ b/typo3/sysext/workspaces/Classes/Controller/Remote/ActionHandler.php
@@ -208,6 +208,7 @@ public function loadColumnModel()
      */
     public function sendToNextStageWindow($uid, $table, $t3ver_oid)
     {
+        $uid = (int)$uid;
         $elementRecord = BackendUtility::getRecord($table, $uid);
         if (is_array($elementRecord)) {
             $workspaceRecord = WorkspaceRecord::get($elementRecord['t3ver_wsid']);
@@ -239,6 +240,7 @@ public function sendToNextStageWindow($uid, $table, $t3ver_oid)
      */
     public function sendToPrevStageWindow($uid, $table)
     {
+        $uid = (int)$uid;
         $elementRecord = BackendUtility::getRecord($table, $uid);
         if (is_array($elementRecord)) {
             $workspaceRecord = WorkspaceRecord::get($elementRecord['t3ver_wsid']);
@@ -282,7 +284,7 @@ public function sendToSpecificStageWindow($nextStageId, array $elements)
         foreach ($elements as $element) {
             $this->stagesService->getRecordService()->add(
                 $element->table,
-                $element->uid
+                (int)$element->uid
             );
         }
 
@@ -616,7 +618,7 @@ public function sendToSpecificStageExecute(\stdClass $parameters)
     protected function getSentToStageWindow($nextStage)
     {
         if (!$nextStage instanceof StageRecord) {
-            $nextStage = WorkspaceRecord::get($this->getCurrentWorkspace())->getStage($nextStage);
+            $nextStage = WorkspaceRecord::get($this->getCurrentWorkspace())->getStage((int)$nextStage);
         }
 
         $result = [];
diff --git a/typo3/sysext/workspaces/Classes/Controller/Remote/MassActionHandler.php b/typo3/sysext/workspaces/Classes/Controller/Remote/MassActionHandler.php
index 914b0df2a3ba..05c325824db3 100644
--- a/typo3/sysext/workspaces/Classes/Controller/Remote/MassActionHandler.php
+++ b/typo3/sysext/workspaces/Classes/Controller/Remote/MassActionHandler.php
@@ -32,10 +32,7 @@ class MassActionHandler
 {
     public const MAX_RECORDS_TO_PROCESS = 30;
 
-    /**
-     * @var WorkspaceService
-     */
-    protected $workspaceService;
+    protected WorkspaceService $workspaceService;
 
     public function __construct()
     {
@@ -44,10 +41,8 @@ public function __construct()
 
     /**
      * Publishes the current workspace.
-     *
-     * @return array
      */
-    public function publishWorkspace(\stdClass $parameters)
+    public function publishWorkspace(\stdClass $parameters): array
     {
         $result = [
             'init' => false,
@@ -72,10 +67,8 @@ public function publishWorkspace(\stdClass $parameters)
 
     /**
      * Flushes the current workspace.
-     *
-     * @return array
      */
-    public function flushWorkspace(\stdClass $parameters)
+    public function flushWorkspace(\stdClass $parameters): array
     {
         $result = [
             'init' => false,
@@ -99,15 +92,11 @@ public function flushWorkspace(\stdClass $parameters)
 
     /**
      * Initializes the command map to be used for publishing.
-     *
-     * @param int $workspace
-     * @param int $language
-     * @return int
      */
-    protected function initPublishData($workspace, $language = null)
+    protected function initPublishData(int $workspace, int $language = null): int
     {
-        // workspace might be -98 a.k.a "All Workspaces but that's save here
-        $publishData = $this->workspaceService->getCmdArrayForPublishWS($workspace, false, 0, $language);
+        // workspace might be -98 a.k.a "All Workspaces" but that's safe here
+        $publishData = $this->workspaceService->getCmdArrayForPublishWS($workspace, false, $language);
         $recordCount = 0;
         foreach ($publishData as $table => $recs) {
             $recordCount += count($recs);
@@ -122,15 +111,11 @@ protected function initPublishData($workspace, $language = null)
 
     /**
      * Initializes the command map to be used for flushing.
-     *
-     * @param int $workspace
-     * @param int $language
-     * @return int
      */
-    protected function initFlushData($workspace, $language = null)
+    protected function initFlushData(int $workspace, int $language = null): int
     {
-        // workspace might be -98 a.k.a "All Workspaces but that's save here
-        $flushData = $this->workspaceService->getCmdArrayForFlushWS($workspace, true, 0, $language);
+        // workspace might be -98 a.k.a "All Workspaces" but that's safe here
+        $flushData = $this->workspaceService->getCmdArrayForFlushWS($workspace, $language);
         $recordCount = 0;
         foreach ($flushData as $table => $recs) {
             $recordCount += count($recs);
@@ -145,10 +130,8 @@ protected function initFlushData($workspace, $language = null)
 
     /**
      * Processes the data.
-     *
-     * @return int
      */
-    protected function processData()
+    protected function processData(): int
     {
         $processData = $this->getBackendUser()->getSessionData('workspaceMassAction');
         $recordsProcessed = $this->getBackendUser()->getSessionData('workspaceMassAction_processed');
@@ -195,10 +178,8 @@ protected function processData()
     /**
      * Validates whether the submitted language parameter can be
      * interpreted as integer value.
-     *
-     * @return int|null
      */
-    protected function validateLanguageParameter(\stdClass $parameters)
+    protected function validateLanguageParameter(\stdClass $parameters): ?int
     {
         $language = null;
         if (isset($parameters->language) && MathUtility::canBeInterpretedAsInteger($parameters->language)) {
@@ -209,8 +190,6 @@ protected function validateLanguageParameter(\stdClass $parameters)
 
     /**
      * Gets the current workspace ID.
-     *
-     * @return int The current workspace ID
      */
     protected function getCurrentWorkspace(): int
     {
diff --git a/typo3/sysext/workspaces/Classes/Controller/Remote/RemoteServer.php b/typo3/sysext/workspaces/Classes/Controller/Remote/RemoteServer.php
index c84e65476b54..8757bade02b3 100644
--- a/typo3/sysext/workspaces/Classes/Controller/Remote/RemoteServer.php
+++ b/typo3/sysext/workspaces/Classes/Controller/Remote/RemoteServer.php
@@ -99,11 +99,11 @@ public function getWorkspaceInfos($parameter, ServerRequestInterface $request)
         }
         $versions = $this->workspaceService->selectVersionsInWorkspace(
             $this->getCurrentWorkspace(),
-            $parameter->stage,
+            (int)$parameter->stage,
             $pageId,
-            $parameter->depth,
+            (int)$parameter->depth,
             'tables_select',
-            $parameter->language
+            $parameter->language !== null ? (int)$parameter->language : null
         );
         $data = $this->gridDataService->generateGridListFromVersions($versions, $parameter, $this->getCurrentWorkspace(), $request);
         return $data;
@@ -389,8 +389,8 @@ protected function getCommentsForRecord(array $historyEntries, array $additional
         foreach ($historyEntries as $entry) {
             $preparedEntry = [];
             $beUserRecord = BackendUtility::getRecord('be_users', $entry['userid']);
-            $preparedEntry['stage_title'] = htmlspecialchars($this->stagesService->getStageTitle($entry['history_data']['next']));
-            $preparedEntry['previous_stage_title'] = htmlspecialchars($this->stagesService->getStageTitle($entry['history_data']['current']));
+            $preparedEntry['stage_title'] = htmlspecialchars($this->stagesService->getStageTitle((int)$entry['history_data']['next']));
+            $preparedEntry['previous_stage_title'] = htmlspecialchars($this->stagesService->getStageTitle((int)$entry['history_data']['current']));
             $preparedEntry['user_uid'] = (int)$entry['userid'];
             $preparedEntry['user_username'] = is_array($beUserRecord) ? htmlspecialchars($beUserRecord['username']) : '';
             $preparedEntry['tstamp'] = htmlspecialchars(BackendUtility::datetime($entry['tstamp']));
@@ -404,7 +404,7 @@ protected function getCommentsForRecord(array $historyEntries, array $additional
             $sysLogEntry = [];
             $data = $this->unserializeLogData($sysLogRow['log_data'] ?? '');
             $beUserRecord = BackendUtility::getRecord('be_users', $sysLogRow['userid']);
-            $sysLogEntry['stage_title'] = htmlspecialchars($this->stagesService->getStageTitle($data['stage']));
+            $sysLogEntry['stage_title'] = htmlspecialchars($this->stagesService->getStageTitle((int)$data['stage']));
             $sysLogEntry['previous_stage_title'] = '';
             $sysLogEntry['user_uid'] = (int)$sysLogRow['userid'];
             $sysLogEntry['user_username'] = is_array($beUserRecord) ? htmlspecialchars($beUserRecord['username']) : '';
@@ -467,10 +467,9 @@ protected function getLanguageService(): LanguageService
      * given set of affected elements.
      *
      * @param CombinedRecord[] $affectedElements
-     * @return IntegrityService
      * @see getAffectedElements
      */
-    protected function createIntegrityService(array $affectedElements)
+    protected function createIntegrityService(array $affectedElements): IntegrityService
     {
         $integrityService = GeneralUtility::makeInstance(IntegrityService::class);
         $integrityService->setAffectedElements($affectedElements);
@@ -482,15 +481,13 @@ protected function createIntegrityService(array $affectedElements)
      * Affected elements have a dependency, e.g. translation overlay
      * and the default origin record - thus, the default record would be
      * affected if the translation overlay shall be published.
-     *
-     * @return array
      */
-    protected function getAffectedElements(\stdClass $parameters)
+    protected function getAffectedElements(\stdClass $parameters): array
     {
         $affectedElements = [];
         if ($parameters->type === 'selection') {
             foreach ((array)$parameters->selection as $element) {
-                $affectedElements[] = CombinedRecord::create($element->table, $element->liveId, $element->versionId);
+                $affectedElements[] = CombinedRecord::create($element->table, (int)$element->liveId, (int)$element->versionId);
             }
         } elseif ($parameters->type === 'all') {
             $versions = $this->workspaceService->selectVersionsInWorkspace(
@@ -503,7 +500,7 @@ protected function getAffectedElements(\stdClass $parameters)
             );
             foreach ($versions as $table => $tableElements) {
                 foreach ($tableElements as $element) {
-                    $affectedElement = CombinedRecord::create($table, $element['t3ver_oid'], $element['uid']);
+                    $affectedElement = CombinedRecord::create($table, (int)$element['t3ver_oid'], (int)$element['uid']);
                     $affectedElement->getVersionRecord()->setRow($element);
                     $affectedElements[] = $affectedElement;
                 }
@@ -515,10 +512,8 @@ protected function getAffectedElements(\stdClass $parameters)
     /**
      * Validates whether the submitted language parameter can be
      * interpreted as integer value.
-     *
-     * @return int|null
      */
-    protected function validateLanguageParameter(\stdClass $parameters)
+    protected function validateLanguageParameter(\stdClass $parameters): ?int
     {
         $language = null;
         if (isset($parameters->language) && MathUtility::canBeInterpretedAsInteger($parameters->language)) {
@@ -529,10 +524,8 @@ protected function validateLanguageParameter(\stdClass $parameters)
 
     /**
      * Gets the current workspace ID.
-     *
-     * @return int The current workspace ID
      */
-    protected function getCurrentWorkspace()
+    protected function getCurrentWorkspace(): int
     {
         return $this->workspaceService->getCurrentWorkspace();
     }
diff --git a/typo3/sysext/workspaces/Classes/DataHandler/CommandMap.php b/typo3/sysext/workspaces/Classes/DataHandler/CommandMap.php
index 6abe64acf6a6..1fb728c31711 100644
--- a/typo3/sysext/workspaces/Classes/DataHandler/CommandMap.php
+++ b/typo3/sysext/workspaces/Classes/DataHandler/CommandMap.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -40,29 +42,12 @@ class CommandMap
     public const KEY_UpdateGetIdCallback = 'KEY_UpdateGetIdCallback';
     public const KEY_TransformDependentElementsToUseLiveId = 'KEY_TransformDependentElementsToUseLiveId';
 
-    /**
-     * @var array
-     */
-    protected $commandMap = [];
-
+    protected array $commandMap = [];
     protected int $workspace;
+    protected array $scopes = [];
+    protected ?ElementEntityProcessor $elementEntityProcessor;
 
-    /**
-     * @var array
-     */
-    protected $scopes;
-
-    /**
-     * @var ElementEntityProcessor|null
-     */
-    protected $elementEntityProcessor;
-
-    /**
-     * Creates this object.
-     *
-     * @param int $workspace
-     */
-    public function __construct(array $commandMap, $workspace)
+    public function __construct(array $commandMap, int $workspace)
     {
         $this->set($commandMap);
         $this->setWorkspace($workspace);
@@ -71,20 +56,16 @@ public function __construct(array $commandMap, $workspace)
 
     /**
      * Gets the command map.
-     *
-     * @return array
      */
-    public function get()
+    public function get(): array
     {
         return $this->commandMap;
     }
 
     /**
      * Sets the command map.
-     *
-     * @return CommandMap
      */
-    public function set(array $commandMap)
+    public function set(array $commandMap): self
     {
         $this->commandMap = $commandMap;
         return $this;
@@ -92,12 +73,10 @@ public function set(array $commandMap)
 
     /**
      * Sets the current workspace.
-     *
-     * @param int $workspace
      */
-    public function setWorkspace($workspace)
+    public function setWorkspace(int $workspace): void
     {
-        $this->workspace = (int)$workspace;
+        $this->workspace = $workspace;
     }
 
     /**
@@ -110,10 +89,8 @@ public function getWorkspace(): int
 
     /**
      * Gets the element entity processor.
-     *
-     * @return ElementEntityProcessor
      */
-    protected function getElementEntityProcessor()
+    protected function getElementEntityProcessor(): ElementEntityProcessor
     {
         if (!isset($this->elementEntityProcessor)) {
             $this->elementEntityProcessor = GeneralUtility::makeInstance(ElementEntityProcessor::class);
@@ -124,10 +101,8 @@ protected function getElementEntityProcessor()
 
     /**
      * Processes the command map.
-     *
-     * @return CommandMap
      */
-    public function process()
+    public function process(): self
     {
         $this->resolveWorkspacesSwapDependencies();
         $this->resolveWorkspacesSetStageDependencies();
@@ -141,7 +116,7 @@ public function process()
      * but not published with this request, are removed from the command map. Otherwise
      * this would produce hanging record sets and lost references.
      */
-    protected function resolveWorkspacesSwapDependencies()
+    protected function resolveWorkspacesSwapDependencies(): void
     {
         $scope = self::SCOPE_WorkspacesSwap;
         $dependency = $this->getDependencyUtility($scope);
@@ -162,22 +137,18 @@ protected function resolveWorkspacesSwapDependencies()
 
     /**
      * Adds workspaces elements for swapping/publishing.
-     *
-     * @param string $table
-     * @param int $liveId
      */
-    protected function addWorkspacesSwapElements(DependencyResolver $dependency, $table, $liveId, array $properties)
+    protected function addWorkspacesSwapElements(DependencyResolver $dependency, string $table, int $liveId, array $properties): void
     {
-        $dependency->addElement($table, $properties['swapWith'], ['liveId' => $liveId, 'properties' => $properties]);
+        $dependency->addElement($table, (int)$properties['swapWith'], ['liveId' => $liveId, 'properties' => $properties]);
     }
 
     /**
      * Invokes all items for staging with a callback method.
      *
-     * @param string $callbackMethod
      * @param array $arguments Optional leading arguments for the callback method
      */
-    protected function invokeWorkspacesSetStageItems($callbackMethod, array $arguments = [])
+    protected function invokeWorkspacesSetStageItems(string $callbackMethod, array $arguments = []): void
     {
         // Traverses the cmd[] array and fetches the accordant actions:
         foreach ($this->commandMap as $table => $versionIdCollection) {
@@ -198,7 +169,7 @@ protected function invokeWorkspacesSetStageItems($callbackMethod, array $argumen
      * Workspaces records that have children or (relative) parents which are versionized
      * but not staged with this request, are removed from the command map.
      */
-    protected function resolveWorkspacesSetStageDependencies()
+    protected function resolveWorkspacesSetStageDependencies(): void
     {
         $scope = self::SCOPE_WorkspacesSetStage;
         $dependency = $this->getDependencyUtility($scope);
@@ -209,11 +180,8 @@ protected function resolveWorkspacesSetStageDependencies()
 
     /**
      * Adds workspaces elements for staging.
-     *
-     * @param string $table
-     * @param int $versionId
      */
-    protected function addWorkspacesSetStageElements(DependencyResolver $dependency, $table, $versionId, array $properties)
+    protected function addWorkspacesSetStageElements(DependencyResolver $dependency, string $table, int $versionId, array $properties): void
     {
         $dependency->addElement($table, $versionId, ['versionId' => $versionId, 'properties' => $properties]);
     }
@@ -223,7 +191,7 @@ protected function addWorkspacesSetStageElements(DependencyResolver $dependency,
      * Workspaces records that have children or (relative) parents which are versionized
      * but not cleared/flushed with this request, are removed from the command map.
      */
-    protected function resolveWorkspacesClearDependencies()
+    protected function resolveWorkspacesClearDependencies(): void
     {
         $scope = self::SCOPE_WorkspacesClear;
         $dependency = $this->getDependencyUtility($scope);
@@ -242,15 +210,11 @@ protected function resolveWorkspacesClearDependencies()
 
     /**
      * Explodes id-lists in the command map for staging actions.
-     *
-     * @throws \RuntimeException
-     * @param string $table
-     * @param string $versionIdList
      */
-    protected function explodeSetStage($table, $versionIdList, array $properties)
+    protected function explodeSetStage(string $table, string|int $versionIdList, array $properties): void
     {
         $extractedCommandMap = [];
-        $versionIds = GeneralUtility::trimExplode(',', $versionIdList, true);
+        $versionIds = GeneralUtility::trimExplode(',', (string)$versionIdList, true);
         if (count($versionIds) > 1) {
             foreach ($versionIds as $versionId) {
                 if (isset($this->commandMap[$table][$versionId]['version'])) {
@@ -266,10 +230,8 @@ protected function explodeSetStage($table, $versionIdList, array $properties)
     /**
      * Applies the workspaces dependencies and removes incomplete structures or automatically
      * completes them
-     *
-     * @param string $scope
      */
-    protected function applyWorkspacesDependencies(DependencyResolver $dependency, $scope)
+    protected function applyWorkspacesDependencies(DependencyResolver $dependency, string $scope): void
     {
         $transformDependentElementsToUseLiveId = $this->getScopeData($scope, self::KEY_TransformDependentElementsToUseLiveId);
         $elementsToBeVersioned = $dependency->getElements();
@@ -295,10 +257,8 @@ protected function applyWorkspacesDependencies(DependencyResolver $dependency, $
 
     /**
      * Updates the command map accordant to valid structures and takes care of the correct order.
-     *
-     * @param string $scope
      */
-    protected function update(ElementEntity $intersectingElement, array $elements, $scope)
+    protected function update(ElementEntity $intersectingElement, array $elements, string $scope): void
     {
         $orderedCommandMap = [];
         $commonProperties = [];
@@ -323,9 +283,9 @@ protected function update(ElementEntity $intersectingElement, array $elements, $
     }
 
     /**
-     * Merges command map elements to the top of the current command map..
+     * Merges command map elements to the top of the current command map.
      */
-    protected function mergeToTop(array $commandMap)
+    protected function mergeToTop(array $commandMap): void
     {
         ArrayUtility::mergeRecursiveWithOverrule($commandMap, $this->commandMap);
         $this->commandMap = $commandMap;
@@ -334,19 +294,15 @@ protected function mergeToTop(array $commandMap)
     /**
      * Merges command map elements to the bottom of the current command map.
      */
-    protected function mergeToBottom(array $commandMap)
+    protected function mergeToBottom(array $commandMap): void
     {
         ArrayUtility::mergeRecursiveWithOverrule($this->commandMap, $commandMap);
     }
 
     /**
      * Removes an element from the command map.
-     *
-     * @param string $table
-     * @param string $id
-     * @param string $command (optional)
      */
-    protected function remove($table, $id, $command = null)
+    protected function remove(string $table, int|string $id, string $command = null): void
     {
         if (is_string($command)) {
             unset($this->commandMap[$table][$id][$command]);
@@ -357,30 +313,24 @@ protected function remove($table, $id, $command = null)
 
     /**
      * Callback to get the liveId of a dependent element.
-     *
-     * @return int
      */
-    protected function getElementLiveIdCallback(ElementEntity $element)
+    protected function getElementLiveIdCallback(ElementEntity $element): int
     {
         return $element->getDataValue('liveId');
     }
 
     /**
      * Callback to get the real id of a dependent element.
-     *
-     * @return int
      */
-    protected function getElementIdCallback(ElementEntity $element)
+    protected function getElementIdCallback(ElementEntity $element): int
     {
         return $element->getId();
     }
 
     /**
      * Callback to get the specific properties of a dependent element for swapping/publishing.
-     *
-     * @return array
      */
-    protected function getElementSwapPropertiesCallback(ElementEntity $element)
+    protected function getElementSwapPropertiesCallback(ElementEntity $element): array
     {
         return [
             'swapWith' => $element->getId(),
@@ -404,10 +354,8 @@ protected function getCommonClearPropertiesCallback(ElementEntity $element)
 
     /**
      * Callback to get common properties of dependent elements for swapping/publishing.
-     *
-     * @return array
      */
-    protected function getCommonSwapPropertiesCallback(ElementEntity $element)
+    protected function getCommonSwapPropertiesCallback(ElementEntity $element): array
     {
         $commonSwapProperties = [];
         $elementProperties = $element->getDataValue('properties');
@@ -426,20 +374,16 @@ protected function getCommonSwapPropertiesCallback(ElementEntity $element)
 
     /**
      * Callback to get the specific properties of a dependent element for staging.
-     *
-     * @return array
      */
-    protected function getElementSetStagePropertiesCallback(ElementEntity $element)
+    protected function getElementSetStagePropertiesCallback(ElementEntity $element): array
     {
         return $this->getCommonSetStagePropertiesCallback($element);
     }
 
     /**
      * Callback to get common properties of dependent elements for staging.
-     *
-     * @return array
      */
-    protected function getCommonSetStagePropertiesCallback(ElementEntity $element)
+    protected function getCommonSetStagePropertiesCallback(ElementEntity $element): array
     {
         $commonSetStageProperties = [];
         $elementProperties = $element->getDataValue('properties');
@@ -482,9 +426,9 @@ protected function getDependencyUtility(string $scope): DependencyResolver
 
     /**
      * Constructs the scope settings.
-     * Currently the scopes for swapping/publishing and staging are available.
+     * Currently, the scopes for swapping/publishing and staging are available.
      */
-    protected function constructScopes()
+    protected function constructScopes(): void
     {
         $this->scopes = [
             // settings for publishing and swapping:
@@ -544,12 +488,9 @@ protected function constructScopes()
     /**
      * Gets data for a particular scope.
      *
-     * @throws \RuntimeException
      * @param string $scope Scope identifier
-     * @param string $key
-     * @return string
      */
-    protected function getScopeData($scope, $key)
+    protected function getScopeData(string $scope, string $key): null|bool|string
     {
         if (!isset($this->scopes[$scope])) {
             throw new \RuntimeException('Scope "' . $scope . '" is not defined.', 1289342187);
@@ -559,11 +500,8 @@ protected function getScopeData($scope, $key)
 
     /**
      * Gets a new callback to be used in the dependency resolver utility.
-     *
-     * @param string $method
-     * @return EventCallback
      */
-    protected function getDependencyCallback($method, array $targetArguments = [])
+    protected function getDependencyCallback(string $method, array $targetArguments = []): EventCallback
     {
         return GeneralUtility::makeInstance(
             EventCallback::class,
@@ -575,11 +513,8 @@ protected function getDependencyCallback($method, array $targetArguments = [])
 
     /**
      * Processes a local callback inside this object.
-     *
-     * @param string $method
-     * @return mixed
      */
-    protected function processCallback($method, array $callbackArguments)
+    protected function processCallback(string $method, array $callbackArguments): mixed
     {
         return $this->$method(...$callbackArguments);
     }
diff --git a/typo3/sysext/workspaces/Classes/Dependency/DependencyEntityFactory.php b/typo3/sysext/workspaces/Classes/Dependency/DependencyEntityFactory.php
index 471dd3822473..4828d8e94826 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/DependencyEntityFactory.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/DependencyEntityFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -22,25 +24,13 @@
  */
 class DependencyEntityFactory
 {
-    /**
-     * @var array
-     */
-    protected $elements = [];
-
-    /**
-     * @var array
-     */
-    protected $references = [];
+    protected array $elements = [];
+    protected array $references = [];
 
     /**
      * Gets and registers a new element.
-     *
-     * @param string $table
-     * @param int $id
-     * @param array $data (optional)
-     * @return ElementEntity
      */
-    public function getElement($table, $id, array $data, DependencyResolver $dependency)
+    public function getElement(string $table, int $id, array $data, DependencyResolver $dependency): ElementEntity
     {
         $element = GeneralUtility::makeInstance(ElementEntity::class, $table, $id, $data, $dependency);
         $elementName = $element->__toString();
@@ -52,11 +42,8 @@ public function getElement($table, $id, array $data, DependencyResolver $depende
 
     /**
      * Gets and registers a new reference.
-     *
-     * @param string $field
-     * @return ReferenceEntity
      */
-    public function getReference(ElementEntity $element, $field)
+    public function getReference(ElementEntity $element, string $field): ReferenceEntity
     {
         $referenceName = $element->__toString() . '.' . $field;
         if (!isset($this->references[$referenceName][$field])) {
@@ -68,15 +55,10 @@ public function getReference(ElementEntity $element, $field)
     /**
      * Gets and registers a new reference.
      *
-     * @param string $table
-     * @param int $id
-     * @param string $field
-     * @param array $data (optional)
-     * @return ReferenceEntity
      * @see getElement
      * @see getReference
      */
-    public function getReferencedElement($table, $id, $field, array $data, DependencyResolver $dependency)
+    public function getReferencedElement(string $table, int $id, string $field, array $data, DependencyResolver $dependency): ReferenceEntity
     {
         return $this->getReference($this->getElement($table, $id, $data, $dependency), $field);
     }
diff --git a/typo3/sysext/workspaces/Classes/Dependency/DependencyResolver.php b/typo3/sysext/workspaces/Classes/Dependency/DependencyResolver.php
index 4afd8a935591..5b0011c9a090 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/DependencyResolver.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/DependencyResolver.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -22,63 +24,33 @@
  */
 class DependencyResolver
 {
-    /**
-     * @var int
-     */
-    protected $workspace = 0;
-
-    /**
-     * @var DependencyEntityFactory|null
-     */
-    protected $factory;
-
-    /**
-     * @var array
-     */
-    protected $elements = [];
-
-    /**
-     * @var array
-     */
-    protected $eventCallbacks = [];
-
-    /**
-     * @var bool
-     */
-    protected $outerMostParentsRequireReferences = false;
-
-    /**
-     * @var array|null
-     */
-    protected $outerMostParents;
+    protected int $workspace = 0;
+    protected ?DependencyEntityFactory $factory;
+    protected array $elements = [];
+    protected array $eventCallbacks = [];
+    protected bool $outerMostParentsRequireReferences = false;
+    protected ?array $outerMostParents;
 
     /**
      * Sets the current workspace.
-     *
-     * @param int $workspace
      */
-    public function setWorkspace($workspace)
+    public function setWorkspace(int $workspace): void
     {
-        $this->workspace = (int)$workspace;
+        $this->workspace = $workspace;
     }
 
     /**
      * Gets the current workspace.
-     *
-     * @return int
      */
-    public function getWorkspace()
+    public function getWorkspace(): int
     {
         return $this->workspace;
     }
 
     /**
      * Sets a callback for a particular event.
-     *
-     * @param string $eventName
-     * @return DependencyResolver
      */
-    public function setEventCallback($eventName, EventCallback $callback)
+    public function setEventCallback(string $eventName, EventCallback $callback): self
     {
         $this->eventCallbacks[$eventName] = $callback;
         return $this;
@@ -86,12 +58,8 @@ public function setEventCallback($eventName, EventCallback $callback)
 
     /**
      * Executes a registered callback (if any) for a particular event.
-     *
-     * @param string $eventName
-     * @param object $caller
-     * @return mixed
      */
-    public function executeEventCallback($eventName, $caller, array $callerArguments = [])
+    public function executeEventCallback(string $eventName, object $caller, array $callerArguments = []): mixed
     {
         if (isset($this->eventCallbacks[$eventName])) {
             /** @var EventCallback $callback */
@@ -103,11 +71,8 @@ public function executeEventCallback($eventName, $caller, array $callerArguments
 
     /**
      * Sets the condition that outermost parents required at least one child or parent reference.
-     *
-     * @param bool $outerMostParentsRequireReferences
-     * @return DependencyResolver
      */
-    public function setOuterMostParentsRequireReferences($outerMostParentsRequireReferences)
+    public function setOuterMostParentsRequireReferences(bool $outerMostParentsRequireReferences): self
     {
         $this->outerMostParentsRequireReferences = (bool)$outerMostParentsRequireReferences;
         return $this;
@@ -115,12 +80,8 @@ public function setOuterMostParentsRequireReferences($outerMostParentsRequireRef
 
     /**
      * Adds an element to be checked for dependent references.
-     *
-     * @param string $table
-     * @param int $id
-     * @return ElementEntity
      */
-    public function addElement($table, $id, array $data = [])
+    public function addElement(string $table, int $id, array $data = []): ElementEntity
     {
         $element = $this->getFactory()->getElement($table, $id, $data, $this);
         $elementName = $element->__toString();
@@ -131,9 +92,9 @@ public function addElement($table, $id, array $data = [])
     /**
      * Gets the outermost parents that define complete dependent structure each.
      *
-     * @return array|ElementEntity[]
+     * @return ElementEntity[]
      */
-    public function getOuterMostParents()
+    public function getOuterMostParents(): array
     {
         if (!isset($this->outerMostParents)) {
             $this->outerMostParents = [];
@@ -148,7 +109,7 @@ public function getOuterMostParents()
     /**
      * Processes and registers the outermost parents accordant to the registered elements.
      */
-    protected function processOuterMostParent(ElementEntity $element)
+    protected function processOuterMostParent(ElementEntity $element): void
     {
         if ($this->outerMostParentsRequireReferences === false || $element->hasReferences()) {
             $outerMostParent = $element->getOuterMostParent();
@@ -163,11 +124,8 @@ protected function processOuterMostParent(ElementEntity $element)
 
     /**
      * Gets all nested elements (including the parent) of a particular outermost parent element.
-     *
-     * @throws \RuntimeException
-     * @return array
      */
-    public function getNestedElements(ElementEntity $outerMostParent)
+    public function getNestedElements(ElementEntity $outerMostParent): array
     {
         $outerMostParentName = $outerMostParent->__toString();
         if (!isset($this->outerMostParents[$outerMostParentName])) {
@@ -179,20 +137,16 @@ public function getNestedElements(ElementEntity $outerMostParent)
 
     /**
      * Gets the registered elements.
-     *
-     * @return array
      */
-    public function getElements()
+    public function getElements(): array
     {
         return $this->elements;
     }
 
     /**
      * Gets an instance of the factory to keep track of element or reference entities.
-     *
-     * @return DependencyEntityFactory
      */
-    public function getFactory()
+    public function getFactory(): DependencyEntityFactory
     {
         if (!isset($this->factory)) {
             $this->factory = GeneralUtility::makeInstance(DependencyEntityFactory::class);
diff --git a/typo3/sysext/workspaces/Classes/Dependency/ElementEntity.php b/typo3/sysext/workspaces/Classes/Dependency/ElementEntity.php
index 86cf1f53f3b1..2c48398839a0 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/ElementEntity.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/ElementEntity.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -31,140 +33,73 @@ class ElementEntity
     public const EVENT_CreateParentReference = 'TYPO3\\CMS\\Version\\Dependency\\ElementEntity::createParentReference';
     public const RESPONSE_Skip = 'TYPO3\\CMS\\Version\\Dependency\\ElementEntity->skip';
 
-    /**
-     * @var bool
-     */
-    protected $invalid = false;
-
-    /**
-     * @var string
-     */
-    protected $table;
-
-    /**
-     * @var int
-     */
-    protected $id;
-
-    /**
-     * @var array
-     */
-    protected $data;
-
-    /**
-     * @var array
-     */
-    protected $record;
-
-    /**
-     * @var DependencyResolver
-     */
-    protected $dependency;
-
-    /**
-     * @var array|null
-     */
-    protected $children;
-
-    /**
-     * @var array|null
-     */
-    protected $parents;
-
-    /**
-     * @var bool
-     */
-    protected $traversingParents = false;
-
-    /**
-     * @var ElementEntity|false|null
-     */
-    protected $outerMostParent;
+    protected bool $invalid = false;
+    protected string $table;
+    protected int $id;
+    protected array $data;
+    protected array $record;
+    protected DependencyResolver $dependency;
+    protected ?array $children;
+    protected ?array $parents;
+    protected ElementEntity|false|null $outerMostParent;
 
-    /**
-     * @var array|null
-     */
-    protected $nestedChildren;
+    protected ?array $nestedChildren;
 
-    /**
-     * Creates this object.
-     *
-     * @param string $table
-     * @param int $id
-     * @param array $data (optional)
-     */
-    public function __construct($table, $id, array $data, DependencyResolver $dependency)
+    public function __construct(string $table, int $id, array $data, DependencyResolver $dependency)
     {
         $this->table = $table;
-        $this->id = (int)$id;
+        $this->id = $id;
         $this->data = $data;
         $this->dependency = $dependency;
         $this->dependency->executeEventCallback(self::EVENT_Construct, $this);
     }
 
-    /**
-     * @param bool $invalid
-     */
-    public function setInvalid($invalid)
+    public function setInvalid(bool $invalid): void
     {
-        $this->invalid = (bool)$invalid;
+        $this->invalid = $invalid;
     }
 
-    /**
-     * @return bool
-     */
-    public function isInvalid()
+    public function isInvalid(): bool
     {
         return $this->invalid;
     }
 
     /**
      * Gets the table.
-     *
-     * @return string
      */
-    public function getTable()
+    public function getTable(): string
     {
         return $this->table;
     }
 
     /**
      * Gets the id.
-     *
-     * @return int
      */
-    public function getId()
+    public function getId(): int
     {
         return $this->id;
     }
 
     /**
      * Sets the id.
-     *
-     * @param int $id
      */
-    public function setId($id)
+    public function setId(int $id): void
     {
-        $this->id = (int)$id;
+        $this->id = $id;
     }
 
     /**
      * Gets the data.
-     *
-     * @return array
      */
-    public function getData()
+    public function getData(): array
     {
         return $this->data;
     }
 
     /**
      * Gets a value for a particular key from the data.
-     *
-     * @param string $key
-     * @return mixed
      */
-    public function getDataValue($key)
+    public function getDataValue(string $key): mixed
     {
         $result = null;
         if ($this->hasDataValue($key)) {
@@ -175,42 +110,32 @@ public function getDataValue($key)
 
     /**
      * Sets a value for a particular key in the data.
-     *
-     * @param string $key
-     * @param mixed $value
      */
-    public function setDataValue($key, $value)
+    public function setDataValue(string $key, mixed $value): void
     {
         $this->data[$key] = $value;
     }
 
     /**
      * Determines whether a particular key holds data.
-     *
-     * @param string $key
-     * @return bool
      */
-    public function hasDataValue($key)
+    public function hasDataValue(string $key): bool
     {
         return isset($this->data[$key]);
     }
 
     /**
      * Converts this object for string representation.
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString(): string
     {
         return self::getIdentifier($this->table, $this->id);
     }
 
     /**
      * Gets the parent dependency object.
-     *
-     * @return DependencyResolver
      */
-    public function getDependency()
+    public function getDependency(): DependencyResolver
     {
         return $this->dependency;
     }
@@ -218,9 +143,9 @@ public function getDependency()
     /**
      * Gets all child references.
      *
-     * @return array|ReferenceEntity[]
+     * @return ReferenceEntity[]
      */
-    public function getChildren()
+    public function getChildren(): array
     {
         if (!isset($this->children)) {
             $this->children = [];
@@ -280,9 +205,9 @@ public function getChildren()
     /**
      * Gets all parent references.
      *
-     * @return array|ReferenceEntity[]
+     * @return ReferenceEntity[]
      */
-    public function getParents()
+    public function getParents(): array
     {
         if (!isset($this->parents)) {
             $this->parents = [];
@@ -338,20 +263,16 @@ public function getParents()
 
     /**
      * Determines whether there are child or parent references.
-     *
-     * @return bool
      */
-    public function hasReferences()
+    public function hasReferences(): bool
     {
         return !empty($this->getChildren()) || !empty($this->getParents());
     }
 
     /**
      * Gets the outermost parent element.
-     *
-     * @return ElementEntity|bool
      */
-    public function getOuterMostParent()
+    public function getOuterMostParent(): false|ElementEntity
     {
         if (!isset($this->outerMostParent)) {
             $parents = $this->getParents();
@@ -378,9 +299,9 @@ public function getOuterMostParent()
     /**
      * Gets nested children accumulated.
      *
-     * @return array|ReferenceEntity[]
+     * @return ReferenceEntity[]
      */
-    public function getNestedChildren()
+    public function getNestedChildren(): array
     {
         if (!isset($this->nestedChildren)) {
             $this->nestedChildren = [];
@@ -395,22 +316,16 @@ public function getNestedChildren()
 
     /**
      * Converts the object for string representation.
-     *
-     * @param string $table
-     * @param int $id
-     * @return string
      */
-    public static function getIdentifier($table, $id)
+    public static function getIdentifier(string $table, int $id): string
     {
         return $table . ':' . $id;
     }
 
     /**
      * Gets the database record of this element.
-     *
-     * @return array
      */
-    public function getRecord()
+    public function getRecord(): array
     {
         if (empty($this->record['uid']) || (int)$this->record['uid'] !== $this->getId()) {
             $this->record = [];
diff --git a/typo3/sysext/workspaces/Classes/Dependency/ElementEntityProcessor.php b/typo3/sysext/workspaces/Classes/Dependency/ElementEntityProcessor.php
index f7edf3131af0..72c1f4a63c71 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/ElementEntityProcessor.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/ElementEntityProcessor.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -25,40 +27,26 @@
  */
 class ElementEntityProcessor
 {
-    /**
-     * @var int
-     */
-    protected $workspace;
-
-    /**
-     * @var DataHandler|null
-     */
-    protected $dataHandler;
+    protected int $workspace;
+    protected ?DataHandler $dataHandler;
 
     /**
      * Sets the current workspace.
-     *
-     * @param int $workspace
      */
-    public function setWorkspace($workspace)
+    public function setWorkspace(int $workspace): void
     {
-        $this->workspace = (int)$workspace;
+        $this->workspace = $workspace;
     }
 
     /**
      * Gets the current workspace.
-     *
-     * @return int
      */
-    public function getWorkspace()
+    public function getWorkspace(): int
     {
         return $this->workspace;
     }
 
-    /**
-     * @return DataHandler
-     */
-    public function getDataHandler()
+    public function getDataHandler(): DataHandler
     {
         if (!isset($this->dataHandler)) {
             $this->dataHandler = GeneralUtility::makeInstance(DataHandler::class);
@@ -69,13 +57,11 @@ public function getDataHandler()
     /**
      * Transforms dependent elements to use the liveId as array key.
      *
-     * @param array|ElementEntity[] $elements
-     * @return array
+     * @param ElementEntity[] $elements
      */
-    public function transformDependentElementsToUseLiveId(array $elements)
+    public function transformDependentElementsToUseLiveId(array $elements): array
     {
         $transformedElements = [];
-        /** @var ElementEntity $element */
         foreach ($elements as $element) {
             $elementName = ElementEntity::getIdentifier($element->getTable(), $element->getDataValue('liveId'));
             $transformedElements[$elementName] = $element;
@@ -86,10 +72,9 @@ public function transformDependentElementsToUseLiveId(array $elements)
     /**
      * Callback to determine whether a new child reference shall be considered in the dependency resolver utility.
      *
-     * @param string $eventName
      * @return string|null Skip response (if required)
      */
-    public function createNewDependentElementChildReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, $eventName)
+    public function createNewDependentElementChildReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, string $eventName): ?string
     {
         // skip children in case ancestor is invalid
         if ($caller->isInvalid()) {
@@ -106,10 +91,9 @@ public function createNewDependentElementChildReferenceCallback(array $callerArg
     /**
      * Callback to determine whether a new parent reference shall be considered in the dependency resolver utility.
      *
-     * @param string $eventName
      * @return string|null Skip response (if required)
      */
-    public function createNewDependentElementParentReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, $eventName)
+    public function createNewDependentElementParentReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, string $eventName): ?string
     {
         $fieldConfiguration = BackendUtility::getTcaFieldConfiguration($callerArguments['table'], $callerArguments['field']);
         $inlineFieldType = $this->getDataHandler()->getRelationFieldType($fieldConfiguration);
@@ -123,10 +107,9 @@ public function createNewDependentElementParentReferenceCallback(array $callerAr
      * Callback to determine whether a new child reference shall be considered in the dependency resolver utility.
      * Only elements that are a delete placeholder are considered.
      *
-     * @param string $eventName
      * @return string|null Skip response (if required)
      */
-    public function createClearDependentElementChildReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, $eventName)
+    public function createClearDependentElementChildReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, string $eventName): ?string
     {
         $response = $this->createNewDependentElementChildReferenceCallback($callerArguments, $targetArgument, $caller, $eventName);
         if (empty($response)) {
@@ -142,10 +125,9 @@ public function createClearDependentElementChildReferenceCallback(array $callerA
      * Callback to determine whether a new parent reference shall be considered in the dependency resolver utility.
      * Only elements that are a delete placeholder are considered.
      *
-     * @param string $eventName
      * @return string|null Skip response (if required)
      */
-    public function createClearDependentElementParentReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, $eventName)
+    public function createClearDependentElementParentReferenceCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, string $eventName): ?string
     {
         $response = $this->createNewDependentElementParentReferenceCallback($callerArguments, $targetArgument, $caller, $eventName);
         if (empty($response)) {
@@ -159,11 +141,8 @@ public function createClearDependentElementParentReferenceCallback(array $caller
 
     /**
      * Callback to add additional data to new elements created in the dependency resolver utility.
-     *
-     * @throws \RuntimeException
-     * @param string $eventName
      */
-    public function createNewDependentElementCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, $eventName)
+    public function createNewDependentElementCallback(array $callerArguments, array $targetArgument, ElementEntity $caller, string $eventName): void
     {
         if (!BackendUtility::isTableWorkspaceEnabled($caller->getTable())) {
             $caller->setInvalid(true);
diff --git a/typo3/sysext/workspaces/Classes/Dependency/EventCallback.php b/typo3/sysext/workspaces/Classes/Dependency/EventCallback.php
index e7a7655c2af1..7f6a2a125a9d 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/EventCallback.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/EventCallback.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -20,29 +22,11 @@
  */
 class EventCallback
 {
-    /**
-     * @var object
-     */
-    protected $object;
-
-    /**
-     * @var string
-     */
-    protected $method;
+    protected object $object;
+    protected string $method;
+    protected array $targetArguments;
 
-    /**
-     * @var array
-     */
-    protected $targetArguments;
-
-    /**
-     * Creates the objects.
-     *
-     * @param object $object
-     * @param string $method
-     * @param array $targetArguments (optional)
-     */
-    public function __construct($object, $method, array $targetArguments = [])
+    public function __construct(object $object, string $method, array $targetArguments = [])
     {
         $this->object = $object;
         $this->method = $method;
@@ -52,12 +36,8 @@ public function __construct($object, $method, array $targetArguments = [])
 
     /**
      * Executes the callback.
-     *
-     * @param object $caller
-     * @param string $eventName
-     * @return mixed
      */
-    public function execute(array $callerArguments, $caller, $eventName)
+    public function execute(array $callerArguments, object $caller, string $eventName): mixed
     {
         $callable = [$this->object, $this->method];
         if (is_callable($callable)) {
diff --git a/typo3/sysext/workspaces/Classes/Dependency/ReferenceEntity.php b/typo3/sysext/workspaces/Classes/Dependency/ReferenceEntity.php
index f93f0ccbb8e9..da2e5e4d85a8 100644
--- a/typo3/sysext/workspaces/Classes/Dependency/ReferenceEntity.php
+++ b/typo3/sysext/workspaces/Classes/Dependency/ReferenceEntity.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -20,22 +22,10 @@
  */
 class ReferenceEntity
 {
-    /**
-     * @var ElementEntity
-     */
-    protected $element;
-
-    /**
-     * @var string
-     */
-    protected $field;
+    protected ElementEntity $element;
+    protected string $field;
 
-    /**
-     * Creates this object.
-     *
-     * @param string $field
-     */
-    public function __construct(ElementEntity $element, $field)
+    public function __construct(ElementEntity $element, string $field)
     {
         $this->element = $element;
         $this->field = $field;
@@ -43,30 +33,24 @@ public function __construct(ElementEntity $element, $field)
 
     /**
      * Gets the elements.
-     *
-     * @return ElementEntity
      */
-    public function getElement()
+    public function getElement(): ElementEntity
     {
         return $this->element;
     }
 
     /**
      * Gets the field.
-     *
-     * @return string
      */
-    public function getField()
+    public function getField(): string
     {
         return $this->field;
     }
 
     /**
      * Converts this object for string representation.
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString(): string
     {
         return $this->element . '.' . $this->field;
     }
diff --git a/typo3/sysext/workspaces/Classes/Domain/Model/CombinedRecord.php b/typo3/sysext/workspaces/Classes/Domain/Model/CombinedRecord.php
index 37492b7eed63..b14a5a110d67 100644
--- a/typo3/sysext/workspaces/Classes/Domain/Model/CombinedRecord.php
+++ b/typo3/sysext/workspaces/Classes/Domain/Model/CombinedRecord.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -22,20 +24,9 @@
  */
 class CombinedRecord
 {
-    /**
-     * @var string
-     */
-    protected $table;
-
-    /**
-     * @var DatabaseRecord
-     */
-    protected $versionRecord;
-
-    /**
-     * @var DatabaseRecord
-     */
-    protected $liveRecord;
+    protected string $table;
+    protected DatabaseRecord $versionRecord;
+    protected DatabaseRecord $liveRecord;
 
     /**
      * Creates combined record object just by live-id and version-id of database record rows.
@@ -43,9 +34,8 @@ class CombinedRecord
      * @param string $table Name of the database table
      * @param int $liveId Id of the database live-record row
      * @param int $versionId Id of the database version-record row
-     * @return CombinedRecord
      */
-    public static function create($table, $liveId, $versionId)
+    public static function create(string $table, int $liveId, int $versionId): CombinedRecord
     {
         $liveRecord = DatabaseRecord::create($table, $liveId);
         $versionRecord = DatabaseRecord::create($table, $versionId);
@@ -58,21 +48,15 @@ public static function create($table, $liveId, $versionId)
      * @param string $table Name of the database table
      * @param array $liveRow The relevant database live-record row
      * @param array $versionRow The relevant database version-record row
-     * @return CombinedRecord
      */
-    public static function createFromArrays($table, array $liveRow, array $versionRow)
+    public static function createFromArrays(string $table, array $liveRow, array $versionRow): CombinedRecord
     {
         $liveRecord = DatabaseRecord::createFromArray($table, $liveRow);
         $versionRecord = DatabaseRecord::createFromArray($table, $versionRow);
         return GeneralUtility::makeInstance(CombinedRecord::class, $table, $liveRecord, $versionRecord);
     }
 
-    /**
-     * Creates this object.
-     *
-     * @param string $table
-     */
-    public function __construct($table, DatabaseRecord $liveRecord, DatabaseRecord $versionRecord)
+    public function __construct(string $table, DatabaseRecord $liveRecord, DatabaseRecord $versionRecord)
     {
         $this->setTable($table);
         $this->setLiveRecord($liveRecord);
@@ -81,30 +65,24 @@ public function __construct($table, DatabaseRecord $liveRecord, DatabaseRecord $
 
     /**
      * Gets the name of the database table.
-     *
-     * @return string
      */
-    public function getTable()
+    public function getTable(): string
     {
         return $this->table;
     }
 
     /**
      * Sets the name of the database table.
-     *
-     * @param string $table
      */
-    public function setTable($table)
+    public function setTable(string $table): void
     {
         $this->table = $table;
     }
 
     /**
      * Gets the live-record object.
-     *
-     * @return DatabaseRecord
      */
-    public function getLiveRecord()
+    public function getLiveRecord(): DatabaseRecord
     {
         return $this->liveRecord;
     }
@@ -112,17 +90,15 @@ public function getLiveRecord()
     /**
      * Sets the live-record object.
      */
-    public function setLiveRecord(DatabaseRecord $liveRecord)
+    public function setLiveRecord(DatabaseRecord $liveRecord): void
     {
         $this->liveRecord = $liveRecord;
     }
 
     /**
      * Gets the version-record object.
-     *
-     * @return DatabaseRecord
      */
-    public function getVersionRecord()
+    public function getVersionRecord(): DatabaseRecord
     {
         return $this->versionRecord;
     }
@@ -130,27 +106,23 @@ public function getVersionRecord()
     /**
      * Sets the version-record object.
      */
-    public function setVersionRecord(DatabaseRecord $versionRecord)
+    public function setVersionRecord(DatabaseRecord $versionRecord): void
     {
         $this->versionRecord = $versionRecord;
     }
 
     /**
      * Gets the id of the live-record.
-     *
-     * @return int
      */
-    public function getLiveId()
+    public function getLiveId(): int
     {
         return $this->getLiveRecord()->getUid();
     }
 
     /**
      * Gets the id of version-record.
-     *
-     * @return int
      */
-    public function getVersiondId()
+    public function getVersiondId(): int
     {
         return $this->getVersionRecord()->getUid();
     }
diff --git a/typo3/sysext/workspaces/Classes/Domain/Model/DatabaseRecord.php b/typo3/sysext/workspaces/Classes/Domain/Model/DatabaseRecord.php
index a67f9ca625ab..63cbdb360cd9 100644
--- a/typo3/sysext/workspaces/Classes/Domain/Model/DatabaseRecord.php
+++ b/typo3/sysext/workspaces/Classes/Domain/Model/DatabaseRecord.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -23,29 +25,17 @@
  */
 class DatabaseRecord
 {
-    /**
-     * @var string
-     */
-    protected $table;
-
-    /**
-     * @var int
-     */
-    protected $uid;
-
-    /**
-     * @var array|null
-     */
-    protected $row;
+    protected string $table;
+    protected int $uid;
+    protected ?array $row;
 
     /**
      * Creates database record object just by id of database record.
      *
      * @param string $table Name of the database table
      * @param int $uid Id of the database record row
-     * @return DatabaseRecord
      */
-    public static function create($table, $uid)
+    public static function create(string $table, int $uid): DatabaseRecord
     {
         return GeneralUtility::makeInstance(DatabaseRecord::class, $table, $uid);
     }
@@ -55,19 +45,13 @@ public static function create($table, $uid)
      *
      * @param string $table Name of the database table
      * @param array $row The relevant database record row
-     * @return DatabaseRecord
      */
-    public static function createFromArray($table, array $row)
+    public static function createFromArray(string $table, array $row): DatabaseRecord
     {
         return GeneralUtility::makeInstance(DatabaseRecord::class, $table, $row['uid'], $row);
     }
 
-    /**
-     * @param string $table Name of the database table
-     * @param int $uid Id of the database record row
-     * @param array|null $row The relevant database record row
-     */
-    public function __construct($table, $uid, array $row = null)
+    public function __construct(string $table, int $uid, array $row = null)
     {
         $this->setTable($table);
         $this->setUid($uid);
@@ -78,50 +62,40 @@ public function __construct($table, $uid, array $row = null)
 
     /**
      * Gets the name of the database table.
-     *
-     * @return string
      */
-    public function getTable()
+    public function getTable(): string
     {
         return $this->table;
     }
 
     /**
      * Sets the name of the database table.
-     *
-     * @param string $table
      */
-    public function setTable($table)
+    public function setTable(string $table): void
     {
         $this->table = $table;
     }
 
     /**
      * Gets the id of the database record row.
-     *
-     * @return int
      */
-    public function getUid()
+    public function getUid(): int
     {
         return $this->uid;
     }
 
     /**
      * Sets the id of the database record row.
-     *
-     * @param int $uid
      */
-    public function setUid($uid)
+    public function setUid(int $uid): void
     {
-        $this->uid = (int)$uid;
+        $this->uid = $uid;
     }
 
     /**
      * Gets the database record row.
-     *
-     * @return array
      */
-    public function getRow()
+    public function getRow(): array
     {
         $this->loadRow();
         return $this->row;
@@ -130,17 +104,15 @@ public function getRow()
     /**
      * Sets the database record row.
      */
-    public function setRow(array $row)
+    public function setRow(array $row): void
     {
         $this->row = $row;
     }
 
     /**
      * Gets the record identifier (table:id).
-     *
-     * @return string
      */
-    public function getIdentifier()
+    public function getIdentifier(): string
     {
         return implode(':', [$this->getTable(), $this->getUid()]);
     }
diff --git a/typo3/sysext/workspaces/Classes/Domain/Record/AbstractRecord.php b/typo3/sysext/workspaces/Classes/Domain/Record/AbstractRecord.php
index 8867bf881cc0..b4d49954a0c9 100644
--- a/typo3/sysext/workspaces/Classes/Domain/Record/AbstractRecord.php
+++ b/typo3/sysext/workspaces/Classes/Domain/Record/AbstractRecord.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -28,12 +30,9 @@
  */
 abstract class AbstractRecord
 {
-    /**
-     * @var array
-     */
-    protected $record;
+    protected array $record;
 
-    protected static function fetch($tableName, $uid)
+    protected static function fetch(string $tableName, int $uid): array
     {
         $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable($tableName);
         $queryBuilder->getRestrictions()->removeAll()->add(GeneralUtility::makeInstance(DeletedRestriction::class));
@@ -68,34 +67,22 @@ public function __construct(array $record)
         $this->record = $record;
     }
 
-    /**
-     * @return string
-     */
-    public function __toString()
+    public function __toString(): string
     {
         return (string)$this->getUid();
     }
 
-    /**
-     * @return int
-     */
-    public function getUid()
+    public function getUid(): int
     {
         return (int)$this->record['uid'];
     }
 
-    /**
-     * @return string
-     */
-    public function getTitle()
+    public function getTitle(): string
     {
         return (string)$this->record['title'];
     }
 
-    /**
-     * @return StagesService
-     */
-    protected function getStagesService()
+    protected function getStagesService(): StagesService
     {
         return GeneralUtility::makeInstance(StagesService::class);
     }
diff --git a/typo3/sysext/workspaces/Classes/Domain/Record/StageRecord.php b/typo3/sysext/workspaces/Classes/Domain/Record/StageRecord.php
index e1d6a6551ab9..a2297b5c54d6 100644
--- a/typo3/sysext/workspaces/Classes/Domain/Record/StageRecord.php
+++ b/typo3/sysext/workspaces/Classes/Domain/Record/StageRecord.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -17,46 +19,16 @@
 
 use TYPO3\CMS\Workspaces\Service\StagesService;
 
-/**
- * Combined record class
- */
 class StageRecord extends AbstractRecord
 {
-    /**
-     * @var WorkspaceRecord
-     */
-    protected $workspace;
-
-    /**
-     * @var bool
-     */
-    protected $internal = false;
-
-    /**
-     * @var array|null
-     */
-    protected $responsiblePersons;
-
-    /**
-     * @var array|null
-     */
-    protected $defaultRecipients;
-
-    /**
-     * @var array|null
-     */
-    protected $preselectedRecipients;
-
-    /**
-     * @var array|null
-     */
-    protected $allRecipients;
-
-    /**
-     * @param int $uid
-     * @return StageRecord|null
-     */
-    public static function get($uid, array $record = null)
+    protected WorkspaceRecord $workspace;
+    protected bool $internal = false;
+    protected array|null $responsiblePersons;
+    protected array|null $defaultRecipients;
+    protected array|null $preselectedRecipients;
+    protected array|null $allRecipients;
+
+    public static function get(int $uid, array $record = null): ?StageRecord
     {
         if (empty($record)) {
             $record = static::fetch('sys_workspace_stage', $uid);
@@ -64,11 +36,7 @@ public static function get($uid, array $record = null)
         return WorkspaceRecord::get($record['parentid'])->getStage($uid);
     }
 
-    /**
-     * @param int $uid
-     * @return StageRecord
-     */
-    public static function build(WorkspaceRecord $workspace, $uid, array $record = null)
+    public static function build(WorkspaceRecord $workspace, int $uid, array $record = null): StageRecord
     {
         if (empty($record)) {
             $record = static::fetch('sys_workspace_stage', $uid);
@@ -82,34 +50,22 @@ public function __construct(WorkspaceRecord $workspace, array $record)
         $this->workspace = $workspace;
     }
 
-    /**
-     * @return WorkspaceRecord
-     */
-    public function getWorkspace()
+    public function getWorkspace(): WorkspaceRecord
     {
         return $this->workspace;
     }
 
-    /**
-     * @return StageRecord|null
-     */
-    public function getPrevious()
+    public function getPrevious(): ?StageRecord
     {
         return $this->getWorkspace()->getPreviousStage($this->getUid());
     }
 
-    /**
-     * @return StageRecord|null
-     */
-    public function getNext()
+    public function getNext(): ?StageRecord
     {
         return $this->getWorkspace()->getNextStage($this->getUid());
     }
 
-    /**
-     * @return int
-     */
-    public function determineOrder(StageRecord $stageRecord)
+    public function determineOrder(StageRecord $stageRecord): int
     {
         if ($this->getUid() === $stageRecord->getUid()) {
             return 0;
@@ -125,10 +81,8 @@ public function determineOrder(StageRecord $stageRecord)
 
     /**
      * Determines whether $this is in a previous stage compared to $stageRecord.
-     *
-     * @return bool
      */
-    public function isPreviousTo(StageRecord $stageRecord)
+    public function isPreviousTo(StageRecord $stageRecord): bool
     {
         $current = $stageRecord;
         while ($previous = $current->getPrevious()) {
@@ -142,10 +96,8 @@ public function isPreviousTo(StageRecord $stageRecord)
 
     /**
      * Determines whether $this is in a later stage compared to $stageRecord.
-     *
-     * @return bool
      */
-    public function isNextTo(StageRecord $stageRecord)
+    public function isNextTo(StageRecord $stageRecord): bool
     {
         $current = $stageRecord;
         while ($next = $current->getNext()) {
@@ -157,10 +109,7 @@ public function isNextTo(StageRecord $stageRecord)
         return false;
     }
 
-    /**
-     * @return string
-     */
-    public function getDefaultComment()
+    public function getDefaultComment(): string
     {
         $defaultComment = '';
         if (isset($this->record['default_mailcomment'])) {
@@ -169,90 +118,57 @@ public function getDefaultComment()
         return $defaultComment;
     }
 
-    /**
-     * @param bool $internal
-     */
-    public function setInternal($internal = true)
+    public function setInternal(bool $internal): void
     {
-        $this->internal = (bool)$internal;
+        $this->internal = $internal;
     }
 
-    /**
-     * @return bool
-     */
-    public function isInternal()
+    public function isInternal(): bool
     {
         return $this->internal;
     }
 
-    /**
-     * @return bool
-     */
-    public function isEditStage()
+    public function isEditStage(): bool
     {
         return $this->getUid() === StagesService::STAGE_EDIT_ID;
     }
 
-    /**
-     * @return bool
-     */
-    public function isPublishStage()
+    public function isPublishStage(): bool
     {
         return $this->getUid() === StagesService::STAGE_PUBLISH_ID;
     }
 
-    /**
-     * @return bool
-     */
-    public function isExecuteStage()
+    public function isExecuteStage(): bool
     {
         return $this->getUid() === StagesService::STAGE_PUBLISH_EXECUTE_ID;
     }
 
-    /**
-     * @return bool
-     */
-    public function isDialogEnabled()
+    public function isDialogEnabled(): bool
     {
         return ((int)$this->record['allow_notificaton_settings'] & 1) > 0;
     }
 
-    /**
-     * @return bool
-     */
-    public function isPreselectionChangeable()
+    public function isPreselectionChangeable(): bool
     {
         return ((int)$this->record['allow_notificaton_settings'] & 2) > 0;
     }
 
-    /**
-     * @return bool
-     */
-    public function areOwnersPreselected()
+    public function areOwnersPreselected(): bool
     {
         return ((int)$this->record['notification_preselection'] & 1) > 0;
     }
 
-    /**
-     * @return bool
-     */
-    public function areMembersPreselected()
+    public function areMembersPreselected(): bool
     {
         return ((int)$this->record['notification_preselection'] & 2) > 0;
     }
 
-    /**
-     * @return bool
-     */
-    public function areEditorsPreselected()
+    public function areEditorsPreselected(): bool
     {
         return ((int)$this->record['notification_preselection'] & 4) > 0;
     }
 
-    /**
-     * @return bool
-     */
-    public function areResponsiblePersonsPreselected()
+    public function areResponsiblePersonsPreselected(): bool
     {
         return ((int)$this->record['notification_preselection'] & 8) > 0;
     }
@@ -262,10 +178,7 @@ public function hasDefaultRecipients(): bool
         return $this->record['notification_defaults'] !== '';
     }
 
-    /**
-     * @return bool
-     */
-    public function hasPreselection()
+    public function hasPreselection(): bool
     {
         return
             $this->areOwnersPreselected()
@@ -276,10 +189,7 @@ public function hasPreselection()
         ;
     }
 
-    /**
-     * @return array
-     */
-    public function getResponsiblePersons()
+    public function getResponsiblePersons(): array
     {
         if (!isset($this->responsiblePersons)) {
             $this->responsiblePersons = [];
@@ -290,10 +200,7 @@ public function getResponsiblePersons()
         return $this->responsiblePersons;
     }
 
-    /**
-     * @return array
-     */
-    public function getDefaultRecipients()
+    public function getDefaultRecipients(): array
     {
         if (!isset($this->defaultRecipients)) {
             $this->defaultRecipients = $this->getStagesService()->resolveBackendUserIds($this->record['notification_defaults']);
@@ -303,10 +210,8 @@ public function getDefaultRecipients()
 
     /**
      * Gets all recipients (backend user ids).
-     *
-     * @return array
      */
-    public function getAllRecipients()
+    public function getAllRecipients(): array
     {
         if (!isset($this->allRecipients)) {
             $allRecipients = $this->getDefaultRecipients();
@@ -330,7 +235,7 @@ public function getAllRecipients()
     /**
      * @return int[]
      */
-    public function getPreselectedRecipients()
+    public function getPreselectedRecipients(): array
     {
         if (!isset($this->preselectedRecipients)) {
             $preselectedRecipients = $this->getDefaultRecipients();
@@ -351,10 +256,7 @@ public function getPreselectedRecipients()
         return $this->preselectedRecipients;
     }
 
-    /**
-     * @return bool
-     */
-    public function isAllowed()
+    public function isAllowed(): bool
     {
         return
             $this->isEditStage()
diff --git a/typo3/sysext/workspaces/Classes/Domain/Record/WorkspaceRecord.php b/typo3/sysext/workspaces/Classes/Domain/Record/WorkspaceRecord.php
index 5011df5ec9a7..5881a52c2405 100644
--- a/typo3/sysext/workspaces/Classes/Domain/Record/WorkspaceRecord.php
+++ b/typo3/sysext/workspaces/Classes/Domain/Record/WorkspaceRecord.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -25,10 +27,7 @@
  */
 class WorkspaceRecord extends AbstractRecord
 {
-    /**
-     * @var array
-     */
-    protected $internalStages = [
+    protected array $internalStages = [
         StagesService::STAGE_EDIT_ID => [
             'name' => 'edit',
             'label' => 'LLL:EXT:workspaces/Resources/Private/Language/locallang_mod_user_ws.xlf:stage_editing',
@@ -43,35 +42,21 @@ class WorkspaceRecord extends AbstractRecord
         ],
     ];
 
-    /**
-     * @var array
-     */
-    protected $internalStageFieldNames = [
+    protected array $internalStageFieldNames = [
         'notification_defaults',
         'notification_preselection',
         'allow_notificaton_settings',
     ];
 
-    /**
-     * @var array|null
-     */
-    protected $owners;
-
-    /**
-     * @var array|null
-     */
-    protected $members;
+    protected ?array $owners;
+    protected ?array $members;
 
     /**
      * @var StageRecord[]|null
      */
-    protected $stages;
+    protected ?array $stages;
 
-    /**
-     * @param int $uid
-     * @return WorkspaceRecord
-     */
-    public static function get($uid, array $record = null)
+    public static function get(int $uid, array $record = null): WorkspaceRecord
     {
         if (empty($uid)) {
             $record = [];
@@ -82,10 +67,7 @@ public static function get($uid, array $record = null)
         return GeneralUtility::makeInstance(self::class, $record);
     }
 
-    /**
-     * @return array
-     */
-    public function getOwners()
+    public function getOwners(): array
     {
         if (!isset($this->owners)) {
             $this->owners = $this->getStagesService()->resolveBackendUserIds($this->record['adminusers']);
@@ -93,10 +75,7 @@ public function getOwners()
         return $this->owners;
     }
 
-    /**
-     * @return array
-     */
-    public function getMembers()
+    public function getMembers(): array
     {
         if (!isset($this->members)) {
             $this->members = $this->getStagesService()->resolveBackendUserIds($this->record['members']);
@@ -107,7 +86,7 @@ public function getMembers()
     /**
      * @return StageRecord[]
      */
-    public function getStages()
+    public function getStages(): array
     {
         if (!isset($this->stages)) {
             $this->stages = [];
@@ -139,13 +118,8 @@ public function getStages()
         return $this->stages;
     }
 
-    /**
-     * @param int $stageId
-     * @return StageRecord|null
-     */
-    public function getStage($stageId)
+    public function getStage(int $stageId): ?StageRecord
     {
-        $stageId = (int)$stageId;
         $this->getStages();
         if (!isset($this->stages[$stageId])) {
             return null;
@@ -153,13 +127,8 @@ public function getStage($stageId)
         return $this->stages[$stageId];
     }
 
-    /**
-     * @param int $stageId
-     * @return StageRecord|null
-     */
-    public function getPreviousStage($stageId)
+    public function getPreviousStage(int $stageId): ?StageRecord
     {
-        $stageId = (int)$stageId;
         $stageIds = array_keys($this->getStages());
         $stageIndex = array_search($stageId, $stageIds);
 
@@ -172,13 +141,8 @@ public function getPreviousStage($stageId)
         return $this->stages[$previousStageId];
     }
 
-    /**
-     * @param int $stageId
-     * @return StageRecord|null
-     */
-    public function getNextStage($stageId)
+    public function getNextStage(int $stageId): ?StageRecord
     {
-        $stageId = (int)$stageId;
         $stageIds = array_keys($this->getStages());
         $stageIndex = array_search($stageId, $stageIds);
 
@@ -190,20 +154,13 @@ public function getNextStage($stageId)
         return $this->stages[$nextStageId];
     }
 
-    protected function addStage(StageRecord $stage)
+    protected function addStage(StageRecord $stage): void
     {
         $this->stages[$stage->getUid()] = $stage;
     }
 
-    /**
-     * @param int $stageId
-     * @return StageRecord
-     * @throws \RuntimeException
-     */
-    protected function createInternalStage($stageId)
+    protected function createInternalStage(int $stageId): StageRecord
     {
-        $stageId = (int)$stageId;
-
         if (!isset($this->internalStages[$stageId])) {
             throw new \RuntimeException('Invalid internal stage "' . $stageId . '"', 1476048246);
         }
diff --git a/typo3/sysext/workspaces/Classes/Hook/BackendUtilityHook.php b/typo3/sysext/workspaces/Classes/Hook/BackendUtilityHook.php
index 8b1b42a21408..9ade13c69bac 100644
--- a/typo3/sysext/workspaces/Classes/Hook/BackendUtilityHook.php
+++ b/typo3/sysext/workspaces/Classes/Hook/BackendUtilityHook.php
@@ -78,7 +78,7 @@ public function displayEditingStagedElementInformation(ModifyEditFormUserAccessE
         }
 
         $stages = GeneralUtility::makeInstance(StagesService::class);
-        $stageName = $stages->getStageTitle($record['t3ver_stage']);
+        $stageName = $stages->getStageTitle((int)$record['t3ver_stage']);
         $editingName = $stages->getStageTitle(StagesService::STAGE_EDIT_ID);
         $message = ($languageService = $this->getLanguageService()) !== null
             ? $languageService->sL('LLL:EXT:workspaces/Resources/Private/Language/locallang.xlf:info.elementAlreadyModified')
diff --git a/typo3/sysext/workspaces/Classes/Service/Dependency/CollectionService.php b/typo3/sysext/workspaces/Classes/Service/Dependency/CollectionService.php
index b74bb00684c1..c2794e0f52fd 100644
--- a/typo3/sysext/workspaces/Classes/Service/Dependency/CollectionService.php
+++ b/typo3/sysext/workspaces/Classes/Service/Dependency/CollectionService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -18,7 +20,6 @@
 use TYPO3\CMS\Core\Authentication\BackendUserAuthentication;
 use TYPO3\CMS\Core\SingletonInterface;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
-use TYPO3\CMS\Workspaces\Dependency;
 use TYPO3\CMS\Workspaces\Dependency\DependencyResolver;
 use TYPO3\CMS\Workspaces\Dependency\ElementEntity;
 use TYPO3\CMS\Workspaces\Dependency\ElementEntityProcessor;
@@ -31,35 +32,12 @@
  */
 class CollectionService implements SingletonInterface
 {
-    /**
-     * @var \TYPO3\CMS\Core\DataHandling\DataHandler
-     */
-    protected $dataHandler;
-
-    /**
-     * @var Dependency\ElementEntityProcessor|null
-     */
-    protected $elementEntityProcessor;
-
-    /**
-     * @var Dependency\DependencyResolver|null
-     */
-    protected $dependencyResolver;
-
-    /**
-     * @var array
-     */
-    protected $dataArray;
-
-    /**
-     * @var array
-     */
-    protected $nestedDataArray;
+    protected ?ElementEntityProcessor $elementEntityProcessor;
+    protected ?DependencyResolver $dependencyResolver = null;
+    protected array $dataArray;
+    protected array $nestedDataArray;
 
-    /**
-     * @return Dependency\DependencyResolver
-     */
-    public function getDependencyResolver()
+    public function getDependencyResolver(): DependencyResolver
     {
         if (!isset($this->dependencyResolver)) {
             $this->dependencyResolver = GeneralUtility::makeInstance(DependencyResolver::class);
@@ -87,11 +65,8 @@ public function getDependencyResolver()
 
     /**
      * Gets a new callback to be used in the dependency resolver utility.
-     *
-     * @param string $method
-     * @return Dependency\EventCallback
      */
-    protected function getDependencyCallback($method, array $targetArguments = [])
+    protected function getDependencyCallback(string $method, array $targetArguments = []): EventCallback
     {
         return GeneralUtility::makeInstance(
             EventCallback::class,
@@ -103,10 +78,8 @@ protected function getDependencyCallback($method, array $targetArguments = [])
 
     /**
      * Gets the element entity processor.
-     *
-     * @return Dependency\ElementEntityProcessor
      */
-    protected function getElementEntityProcessor()
+    protected function getElementEntityProcessor(): ElementEntityProcessor
     {
         if (!isset($this->elementEntityProcessor)) {
             $this->elementEntityProcessor = GeneralUtility::makeInstance(ElementEntityProcessor::class);
@@ -117,10 +90,8 @@ protected function getElementEntityProcessor()
 
     /**
      * Processes the data array
-     *
-     * @return array
      */
-    public function process(array $dataArray)
+    public function process(array $dataArray): array
     {
         $collection = 0;
         $this->dataArray = $dataArray;
@@ -151,10 +122,8 @@ public function process(array $dataArray)
     /**
      * Applies structures to instance data array and
      * ensures children are added below accordant parent
-     *
-     * @return array
      */
-    protected function finalize(array $dataArray)
+    protected function finalize(array $dataArray): array
     {
         $processedDataArray = [];
         foreach ($dataArray as $dataElement) {
@@ -175,12 +144,8 @@ protected function finalize(array $dataArray)
 
     /**
      * Resolves nested child dependencies.
-     *
-     * @param int $collection
-     * @param string $nextParentIdentifier
-     * @param int $collectionLevel
      */
-    protected function resolveDataArrayChildDependencies(ElementEntity $parent, $collection, $nextParentIdentifier = '', $collectionLevel = 0)
+    protected function resolveDataArrayChildDependencies(ElementEntity $parent, int $collection, string $nextParentIdentifier = '', int $collectionLevel = 0): void
     {
         $parentIdentifier = $parent->__toString();
         $parentIsSet = isset($this->dataArray[$parentIdentifier]);
diff --git a/typo3/sysext/workspaces/Classes/Service/GridDataService.php b/typo3/sysext/workspaces/Classes/Service/GridDataService.php
index a929b3f20651..cedae0640713 100644
--- a/typo3/sysext/workspaces/Classes/Service/GridDataService.php
+++ b/typo3/sysext/workspaces/Classes/Service/GridDataService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -39,9 +41,6 @@
 use TYPO3\CMS\Workspaces\Preview\PreviewUriBuilder;
 use TYPO3\CMS\Workspaces\Service\Dependency\CollectionService;
 
-/**
- * Grid data service
- */
 class GridDataService implements LoggerAwareInterface
 {
     use LoggerAwareTrait;
@@ -54,41 +53,26 @@ class GridDataService implements LoggerAwareInterface
 
     /**
      * Id of the current active workspace.
-     *
-     * @var int
      */
-    protected $currentWorkspace;
+    protected int $currentWorkspace = 0;
 
     /**
      * Version record information (filtered, sorted and limited)
-     *
-     * @var array
      */
-    protected $dataArray = [];
+    protected array $dataArray = [];
 
     /**
      * Name of the field used for sorting.
-     *
-     * @var string
      */
-    protected $sort = '';
+    protected string $sort = '';
 
     /**
      * Direction used for sorting (ASC, DESC).
-     *
-     * @var string
      */
-    protected $sortDir = '';
+    protected string $sortDir = '';
 
-    /**
-     * @var FrontendInterface
-     */
-    protected $workspacesCache;
-
-    /**
-     * @var IntegrityService|null
-     */
-    protected $integrityService;
+    protected ?FrontendInterface $workspacesCache;
+    protected ?IntegrityService $integrityService;
 
     public function __construct(
         private readonly EventDispatcherInterface $eventDispatcher,
@@ -103,9 +87,8 @@ public function __construct(
      * @param \stdClass $parameter Parameters as submitted by JavaScript component
      * @param int $currentWorkspace The current workspace
      * @return array Version record information (filtered, sorted and limited)
-     * @throws \InvalidArgumentException
      */
-    public function generateGridListFromVersions($versions, $parameter, $currentWorkspace, ServerRequestInterface $request)
+    public function generateGridListFromVersions(array $versions, \stdClass $parameter, int $currentWorkspace, ServerRequestInterface $request): array
     {
         // Read the given parameters from grid. If the parameter is not set use default values.
         $filterTxt = $parameter->filterTxt ?? '';
@@ -113,11 +96,7 @@ public function generateGridListFromVersions($versions, $parameter, $currentWork
         $limit = isset($parameter->limit) ? (int)$parameter->limit : 30;
         $this->sort = $parameter->sort ?? 't3ver_oid';
         $this->sortDir = $parameter->dir ?? 'ASC';
-        if (is_int($currentWorkspace)) {
-            $this->currentWorkspace = $currentWorkspace;
-        } else {
-            throw new \InvalidArgumentException('No such workspace defined', 1476048304);
-        }
+        $this->currentWorkspace = $currentWorkspace;
         $this->generateDataArray($versions, $filterTxt, $request);
         return [
             // Only count parent records for pagination
@@ -134,7 +113,7 @@ public function generateGridListFromVersions($versions, $parameter, $currentWork
      * @param array $versions All available version records
      * @param string $filterTxt Text to be used to filter record result
      */
-    protected function generateDataArray(array $versions, $filterTxt, ServerRequestInterface $request)
+    protected function generateDataArray(array $versions, string $filterTxt, ServerRequestInterface $request): void
     {
         $backendUser = $this->getBackendUser();
         $workspaceAccess = $backendUser->checkWorkspace($backendUser->workspace);
@@ -165,7 +144,7 @@ protected function generateDataArray(array $versions, $filterTxt, ServerRequestI
                     $this->getIntegrityService()->checkElement($combinedRecord);
 
                     if ($hiddenField !== null) {
-                        $recordState = $this->workspaceState($versionRecord['t3ver_state'], $origRecord[$hiddenField], $versionRecord[$hiddenField], $hasDiff);
+                        $recordState = $this->workspaceState($versionRecord['t3ver_state'], (bool)$origRecord[$hiddenField], (bool)$versionRecord[$hiddenField], $hasDiff);
                     } else {
                         $recordState = $this->workspaceState($versionRecord['t3ver_state'], $hasDiff);
                     }
@@ -199,12 +178,12 @@ protected function generateDataArray(array $versions, $filterTxt, ServerRequestI
                     $versionArray['label_Workspace_crop'] = htmlspecialchars(GeneralUtility::fixed_lgd_cs($workspaceRecordLabel, (int)$backendUser->uc['titleLen']));
                     $versionArray['label_Live'] = htmlspecialchars($liveRecordLabel);
                     $versionArray['label_Live_crop'] = htmlspecialchars(GeneralUtility::fixed_lgd_cs($liveRecordLabel, (int)$backendUser->uc['titleLen']));
-                    $versionArray['label_Stage'] = htmlspecialchars($stagesObj->getStageTitle($versionRecord['t3ver_stage']));
+                    $versionArray['label_Stage'] = htmlspecialchars($stagesObj->getStageTitle((int)$versionRecord['t3ver_stage']));
                     $tempStage = $stagesObj->getNextStage($versionRecord['t3ver_stage']);
-                    $versionArray['label_nextStage'] = htmlspecialchars($stagesObj->getStageTitle($tempStage['uid']));
+                    $versionArray['label_nextStage'] = htmlspecialchars($stagesObj->getStageTitle((int)$tempStage['uid']));
                     $versionArray['value_nextStage'] = (int)$tempStage['uid'];
                     $tempStage = $stagesObj->getPrevStage($versionRecord['t3ver_stage']);
-                    $versionArray['label_prevStage'] = htmlspecialchars($stagesObj->getStageTitle($tempStage['uid'] ?? 0));
+                    $versionArray['label_prevStage'] = htmlspecialchars($stagesObj->getStageTitle((int)($tempStage['uid'] ?? 0)));
                     $versionArray['value_prevStage'] = (int)($tempStage['uid'] ?? 0);
                     $versionArray['path_Live'] = htmlspecialchars(BackendUtility::getRecordPath($record['livepid'], '', 999));
                     $versionArray['path_Workspace'] = htmlspecialchars($pathWorkspace);
@@ -259,9 +238,10 @@ protected function generateDataArray(array $versions, $filterTxt, ServerRequestI
             // Enrich elements after everything has been processed:
             foreach ($this->dataArray as &$element) {
                 $identifier = $element['table'] . ':' . $element['t3ver_oid'];
+                $messages = $this->getIntegrityService()->getIssueMessages($identifier);
                 $element['integrity'] = [
                     'status' => $this->getIntegrityService()->getStatusRepresentation($identifier),
-                    'messages' => htmlspecialchars((string)$this->getIntegrityService()->getIssueMessages($identifier, true)),
+                    'messages' => htmlspecialchars(implode('<br>', $messages)),
                 ];
             }
             $this->setDataArrayIntoCache($versions, $filterTxt);
@@ -279,8 +259,8 @@ protected function versionIsModified(CombinedRecord $combinedRecord, ServerReque
     {
         $remoteServer = GeneralUtility::makeInstance(RemoteServer::class);
 
-        $params = new \StdClass();
-        $params->stage = $combinedRecord->getVersionRecord()->getRow()['t3ver_stage'];
+        $params = new \stdClass();
+        $params->stage = (int)$combinedRecord->getVersionRecord()->getRow()['t3ver_stage'];
         $params->t3ver_oid = $combinedRecord->getLiveRecord()->getUid();
         $params->table = $combinedRecord->getLiveRecord()->getTable();
         $params->uid = $combinedRecord->getVersionRecord()->getUid();
@@ -293,7 +273,7 @@ protected function versionIsModified(CombinedRecord $combinedRecord, ServerReque
      * Resolves dependencies of nested structures
      * and sort data elements considering these dependencies.
      */
-    protected function resolveDataArrayDependencies()
+    protected function resolveDataArrayDependencies(): void
     {
         $collectionService = $this->getDependencyCollectionService();
         $dependencyResolver = $collectionService->getDependencyResolver();
@@ -307,12 +287,8 @@ protected function resolveDataArrayDependencies()
 
     /**
      * Gets the data array by considering the page to be shown in the grid view.
-     *
-     * @param int $start
-     * @param int $limit
-     * @return array
      */
-    protected function getDataArray($start, $limit)
+    protected function getDataArray(int $start, int $limit): array
     {
         $dataArrayCount = count($this->dataArray);
         $start = $this->calculateStartWithCollections($start);
@@ -333,7 +309,7 @@ protected function getDataArray($start, $limit)
     /**
      * Initializes the workspace cache
      */
-    protected function initializeWorkspacesCachingFramework()
+    protected function initializeWorkspacesCachingFramework(): void
     {
         $this->workspacesCache = GeneralUtility::makeInstance(CacheManager::class)->getCache('workspaces_cache');
     }
@@ -344,7 +320,7 @@ protected function initializeWorkspacesCachingFramework()
      * @param array $versions All records uids etc. First key is table name, second key incremental integer. Records are associative arrays with uid and t3ver_oid fields. The pid of the online record is found as "livepid" the pid of the offline record is found in "wspid
      * @param string $filterTxt The given filter text from the grid.
      */
-    protected function setDataArrayIntoCache(array $versions, $filterTxt)
+    protected function setDataArrayIntoCache(array $versions, string $filterTxt): void
     {
         $hash = $this->calculateHash($versions, $filterTxt);
         $this->workspacesCache->set(
@@ -364,7 +340,7 @@ protected function setDataArrayIntoCache(array $versions, $filterTxt)
      * @param string $filterTxt The given filter text from the grid.
      * @return bool TRUE if cache entry was successfully fetched from cache and content put to $this->dataArray
      */
-    protected function getDataArrayFromCache(array $versions, $filterTxt)
+    protected function getDataArrayFromCache(array $versions, string $filterTxt): bool
     {
         $cacheEntry = false;
         $hash = $this->calculateHash($versions, $filterTxt);
@@ -381,9 +357,8 @@ protected function getDataArrayFromCache(array $versions, $filterTxt)
      *
      * @param array $versions All records uids etc. First key is table name, second key incremental integer. Records are associative arrays with uid and t3ver_oid fields. The pid of the online record is found as "livepid" the pid of the offline record is found in "wspid
      * @param string $filterTxt The given filter text from the grid.
-     * @return string
      */
-    protected function calculateHash(array $versions, $filterTxt)
+    protected function calculateHash(array $versions, string $filterTxt): string
     {
         $backendUser = $this->getBackendUser();
         $hashArray = [
@@ -403,7 +378,7 @@ protected function calculateHash(array $versions, $filterTxt)
      * Performs sorting on the data array accordant to the
      * selected column in the grid view to be used for sorting.
      */
-    protected function sortDataArray()
+    protected function sortDataArray(): void
     {
         switch ($this->sort) {
             case 'uid':
@@ -437,12 +412,8 @@ protected function sortDataArray()
 
     /**
      * Implements individual sorting for columns based on integer comparison.
-     *
-     * @param array $a First value
-     * @param array $b Second value
-     * @return int
      */
-    protected function intSort(array $a, array $b)
+    protected function intSort(array $a, array $b): int
     {
         if (!$this->isSortable($a, $b)) {
             return 0;
@@ -469,12 +440,8 @@ protected function intSort(array $a, array $b)
 
     /**
      * Implements individual sorting for columns based on string comparison.
-     *
-     * @param array $a First value
-     * @param array $b Second value
-     * @return int
      */
-    protected function stringSort($a, $b)
+    protected function stringSort(array $a, array $b): int
     {
         if (!$this->isSortable($a, $b)) {
             return 0;
@@ -503,10 +470,8 @@ protected function stringSort($a, $b)
      * Determines whether dataArray elements are sortable.
      * Only elements on the first level (0) or below the same
      * parent element are directly sortable.
-     *
-     * @return bool
      */
-    protected function isSortable(array $a, array $b)
+    protected function isSortable(array $a, array $b): bool
     {
         return
             $a[self::GridColumn_CollectionLevel] === 0 && $b[self::GridColumn_CollectionLevel] === 0
@@ -529,11 +494,8 @@ protected function isPageModuleAllowed(): bool
     /**
      * Determines whether the text used to filter the results is part of
      * a column that is visible in the grid view.
-     *
-     * @param string $filterText
-     * @return bool
      */
-    protected function isFilterTextInVisibleColumns($filterText, array $versionArray)
+    protected function isFilterTextInVisibleColumns(string $filterText, array $versionArray): bool
     {
         $backendUser = $this->getBackendUser();
         if (is_array($backendUser->uc['moduleData']['Workspaces'][$backendUser->workspace]['columns'] ?? false)) {
@@ -581,15 +543,13 @@ protected function isFilterTextInVisibleColumns($filterText, array $versionArray
      * @param bool $hiddenOnline  hidden status of online record
      * @param bool $hiddenOffline hidden status of offline record
      * @param bool $hasDiff    whether the version has any changes
-     *
-     * @return string
      */
-    protected function workspaceState($stateId, $hiddenOnline = false, $hiddenOffline = false, $hasDiff = true)
+    protected function workspaceState(int $stateId, bool $hiddenOnline = false, bool $hiddenOffline = false, bool $hasDiff = true): string
     {
         $hiddenState = null;
-        if ($hiddenOnline == 0 && $hiddenOffline == 1) {
+        if (!$hiddenOnline && $hiddenOffline) {
             $hiddenState = 'hidden';
-        } elseif ($hiddenOnline == 1 && $hiddenOffline == 0) {
+        } elseif ($hiddenOnline && !$hiddenOffline) {
             $hiddenState = 'unhidden';
         }
         switch (VersionState::tryFrom($stateId)) {
@@ -620,7 +580,7 @@ protected function workspaceState($stateId, $hiddenOnline = false, $hiddenOfflin
      * @param string $type Type to be fetches (e.g. 'disabled', 'starttime', 'endtime', 'fe_group)
      * @return string|null The accordant field name or NULL if not defined
      */
-    protected function getTcaEnableColumnsFieldName($table, $type)
+    protected function getTcaEnableColumnsFieldName(string $table, string $type): ?string
     {
         $fieldName = null;
 
@@ -638,13 +598,13 @@ protected function getTcaEnableColumnsFieldName($table, $type)
      * @param array $record Database record
      * @return int
      */
-    protected function getLanguageValue($table, array $record)
+    protected function getLanguageValue(string $table, array $record): int
     {
         $languageValue = 0;
         if (BackendUtility::isTableLocalizable($table)) {
             $languageField = $GLOBALS['TCA'][$table]['ctrl']['languageField'];
             if (!empty($record[$languageField])) {
-                $languageValue = $record[$languageField];
+                $languageValue = (int)$record[$languageField];
             }
         }
         return $languageValue;
@@ -659,10 +619,10 @@ protected function getLanguageValue($table, array $record)
      * @return string|null
      * @see getSystemLanguages
      */
-    protected function getSystemLanguageValue($id, $pageId, $key)
+    protected function getSystemLanguageValue(int $id, int $pageId, string $key): ?string
     {
         $value = null;
-        $systemLanguages = $this->getSystemLanguages((int)$pageId);
+        $systemLanguages = $this->getSystemLanguages($pageId);
         if (!empty($systemLanguages[$id][$key])) {
             $value = $systemLanguages[$id][$key];
         }
@@ -772,20 +732,16 @@ protected function addCollectionChildrenRecursive(array $item, int &$recordsCoun
 
     /**
      * Gets all available system languages.
-     *
-     * @return array
      */
-    protected function getSystemLanguages(int $pageId)
+    protected function getSystemLanguages(int $pageId): array
     {
         return GeneralUtility::makeInstance(TranslationConfigurationProvider::class)->getSystemLanguages($pageId);
     }
 
     /**
      * Gets an instance of the integrity service.
-     *
-     * @return IntegrityService
      */
-    protected function getIntegrityService()
+    protected function getIntegrityService(): IntegrityService
     {
         if (!isset($this->integrityService)) {
             $this->integrityService = GeneralUtility::makeInstance(IntegrityService::class);
@@ -793,10 +749,7 @@ protected function getIntegrityService()
         return $this->integrityService;
     }
 
-    /**
-     * @return Dependency\CollectionService
-     */
-    protected function getDependencyCollectionService()
+    protected function getDependencyCollectionService(): CollectionService
     {
         return GeneralUtility::makeInstance(CollectionService::class);
     }
diff --git a/typo3/sysext/workspaces/Classes/Service/HistoryService.php b/typo3/sysext/workspaces/Classes/Service/HistoryService.php
index caaececd7fcd..3bb5709fb233 100644
--- a/typo3/sysext/workspaces/Classes/Service/HistoryService.php
+++ b/typo3/sysext/workspaces/Classes/Service/HistoryService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -26,24 +28,11 @@
 use TYPO3\CMS\Core\Utility\DiffUtility;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 
-/**
- * Service for history
- */
 class HistoryService implements SingletonInterface
 {
-    /**
-     * @var array
-     */
-    protected $backendUserNames;
-
-    /**
-     * @var array
-     */
-    protected $historyEntries = [];
+    protected array $backendUserNames;
+    protected array $historyEntries = [];
 
-    /**
-     * Creates this object.
-     */
     public function __construct()
     {
         $this->backendUserNames = BackendUtility::getUserNames();
@@ -56,7 +45,7 @@ public function __construct()
      * @param int $id Uid of the record
      * @return array Record history entries
      */
-    public function getHistory($table, $id)
+    public function getHistory(string $table, int $id): array
     {
         $history = [];
         $i = 0;
@@ -90,10 +79,9 @@ public function getStageChanges(string $table, int $id): array
      * record history entry.
      *
      * @param array $entry Record history entry
-     * @return array
      * @see getHistory
      */
-    protected function getHistoryEntry(array $entry)
+    protected function getHistoryEntry(array $entry): array
     {
         if (!empty($entry['action'])) {
             $differences = $entry['action'];
@@ -117,9 +105,8 @@ protected function getHistoryEntry(array $entry)
      * of one record history entry.
      *
      * @param array $entry Record history entry
-     * @return array
      */
-    protected function getDifferences(array $entry)
+    protected function getDifferences(array $entry): array
     {
         $diffUtility = GeneralUtility::makeInstance(DiffUtility::class);
         $differences = [];
@@ -158,11 +145,8 @@ protected function getDifferences(array $entry)
 
     /**
      * Gets the username of a backend user.
-     *
-     * @param string $user
-     * @return string
      */
-    protected function getUserName($user)
+    protected function getUserName(int $user): string
     {
         $userName = 'unknown';
         if (!empty($this->backendUserNames[$user]['username'])) {
@@ -176,9 +160,8 @@ protected function getUserName($user)
      *
      * @param string $table Name of the table
      * @param int $id Uid of the record
-     * @return array
      */
-    protected function getHistoryEntries($table, $id)
+    protected function getHistoryEntries(string $table, int $id): array
     {
         if (!isset($this->historyEntries[$table][$id])) {
             $this->historyEntries[$table][$id] = GeneralUtility::makeInstance(RecordHistory::class)
diff --git a/typo3/sysext/workspaces/Classes/Service/IntegrityService.php b/typo3/sysext/workspaces/Classes/Service/IntegrityService.php
index be62569f109b..f9d5255cf5f0 100644
--- a/typo3/sysext/workspaces/Classes/Service/IntegrityService.php
+++ b/typo3/sysext/workspaces/Classes/Service/IntegrityService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -20,9 +22,6 @@
 use TYPO3\CMS\Core\Versioning\VersionState;
 use TYPO3\CMS\Workspaces\Domain\Model\CombinedRecord;
 
-/**
- * Service for integrity
- */
 class IntegrityService
 {
     /**
@@ -30,7 +29,7 @@ class IntegrityService
      *
      * @var int
      */
-    public const STATUS_Succes = 100;
+    public const STATUS_Success = 100;
     /**
      * Info status - nothing is wrong, but a notice is shown
      *
@@ -49,11 +48,9 @@ class IntegrityService
      * @var int
      */
     public const STATUS_Error = 103;
-    /**
-     * @var array
-     */
-    protected $statusRepresentation = [
-        self::STATUS_Succes => 'success',
+
+    protected array $statusRepresentation = [
+        self::STATUS_Success => 'success',
         self::STATUS_Info => 'info',
         self::STATUS_Warning => 'warning',
         self::STATUS_Error => 'error',
@@ -62,30 +59,28 @@ class IntegrityService
     /**
      * @var CombinedRecord[]
      */
-    protected $affectedElements;
+    protected array $affectedElements = [];
 
     /**
      * Array storing all issues that have been checked and
      * found during runtime in this object. The array keys
      * are identifiers of table and the version-id.
      *
-     * 'tx_table:123' => array(
-     * array(
-     * 'status' => 'warning',
-     * 'message' => 'Element cannot be...',
-     * )
-     * )
-     *
-     * @var array
+     * 'tx_table:123' => [
+     *   [
+     *     'status' => 102,
+     *     'message' => 'Element cannot be...',
+     *   ]
+     * ]
      */
-    protected $issues = [];
+    protected array $issues = [];
 
     /**
      * Sets the affected elements.
      *
      * @param CombinedRecord[] $affectedElements
      */
-    public function setAffectedElements(array $affectedElements)
+    public function setAffectedElements(array $affectedElements): void
     {
         $this->affectedElements = $affectedElements;
     }
@@ -93,7 +88,7 @@ public function setAffectedElements(array $affectedElements)
     /**
      * Checks integrity of affected records.
      */
-    public function check()
+    public function check(): void
     {
         foreach ($this->affectedElements as $affectedElement) {
             $this->checkElement($affectedElement);
@@ -103,7 +98,7 @@ public function check()
     /**
      * Checks a single element.
      */
-    public function checkElement(CombinedRecord $element)
+    public function checkElement(CombinedRecord $element): void
     {
         $this->checkLocalization($element);
     }
@@ -114,7 +109,7 @@ public function checkElement(CombinedRecord $element)
      * is new in this workspace,
      * then both (localization and localization parent) should be published.
      */
-    protected function checkLocalization(CombinedRecord $element)
+    protected function checkLocalization(CombinedRecord $element): void
     {
         $table = $element->getTable();
         if (BackendUtility::isTableLocalizable($table)) {
@@ -150,12 +145,11 @@ protected function checkLocalization(CombinedRecord $element)
      * Gets the status of the most important severity.
      * (low << success, info, warning, error >> high)
      *
-     * @param string $identifier Record identifier (table:id) for look-ups
-     * @return string
+     * @param string|null $identifier Record identifier (table:id) for look-ups
      */
-    public function getStatus($identifier = null)
+    public function getStatus(string $identifier = null): int
     {
-        $status = self::STATUS_Succes;
+        $status = self::STATUS_Success;
         if ($identifier === null) {
             foreach ($this->issues as $idenfieriferIssues) {
                 foreach ($idenfieriferIssues as $issue) {
@@ -175,13 +169,13 @@ public function getStatus($identifier = null)
     }
 
     /**
-     * Gets the (human readable) representation of the status with the most
+     * Gets the (human-readable) representation of the status with the most
      * important severity (wraps $this->getStatus() and translates the result).
      *
-     * @param string $identifier Record identifier (table:id) for look-ups
+     * @param string|null $identifier Record identifier (table:id) for look-ups
      * @return string One out of success, info, warning, error
      */
-    public function getStatusRepresentation($identifier = null)
+    public function getStatusRepresentation(string $identifier = null): string
     {
         return $this->statusRepresentation[$this->getStatus($identifier)];
     }
@@ -189,10 +183,9 @@ public function getStatusRepresentation($identifier = null)
     /**
      * Gets issues, all or specific for one identifier.
      *
-     * @param string $identifier Record identifier (table:id) for look-ups
-     * @return array
+     * @param string|null $identifier Record identifier (table:id) for look-ups
      */
-    public function getIssues($identifier = null)
+    public function getIssues(string $identifier = null): array
     {
         if ($identifier === null) {
             return $this->issues;
@@ -206,11 +199,9 @@ public function getIssues($identifier = null)
     /**
      * Gets the message of all issues.
      *
-     * @param string $identifier Record identifier (table:id) for look-ups
-     * @param bool $asString Return results as string instead of array
-     * @return array|string
+     * @param string|null $identifier Record identifier (table:id) for look-ups
      */
-    public function getIssueMessages($identifier = null, $asString = false)
+    public function getIssueMessages(string $identifier = null): array
     {
         $messages = [];
         if ($identifier === null) {
@@ -224,9 +215,6 @@ public function getIssueMessages($identifier = null, $asString = false)
                 $messages[] = $issue['message'];
             }
         }
-        if ($asString) {
-            $messages = implode('<br/>', $messages);
-        }
         return $messages;
     }
 
@@ -237,7 +225,7 @@ public function getIssueMessages($identifier = null, $asString = false)
      * @param int $status Status code (see constants)
      * @param string $message Message/description of the issue
      */
-    protected function addIssue($identifier, $status, $message)
+    protected function addIssue(string $identifier, int $status, string $message): void
     {
         if (!isset($this->issues[$identifier])) {
             $this->issues[$identifier] = [];
diff --git a/typo3/sysext/workspaces/Classes/Service/RecordService.php b/typo3/sysext/workspaces/Classes/Service/RecordService.php
index 19cfb89ec191..9646ecefb90c 100644
--- a/typo3/sysext/workspaces/Classes/Service/RecordService.php
+++ b/typo3/sysext/workspaces/Classes/Service/RecordService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -20,21 +22,14 @@
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Workspaces\Domain\Model\DatabaseRecord;
 
-/**
- * Service for records
- */
 class RecordService implements SingletonInterface
 {
     /**
      * @var DatabaseRecord[]
      */
-    protected $records = [];
+    protected array $records = [];
 
-    /**
-     * @param string $tableName
-     * @param int $id
-     */
-    public function add($tableName, $id)
+    public function add(string $tableName, int $id): void
     {
         $databaseRecord = DatabaseRecord::create($tableName, $id);
         if (!isset($this->records[$databaseRecord->getIdentifier()])) {
@@ -42,10 +37,7 @@ public function add($tableName, $id)
         }
     }
 
-    /**
-     * @return array
-     */
-    public function getIdsPerTable()
+    public function getIdsPerTable(): array
     {
         $idsPerTable = [];
         foreach ($this->records as $databaseRecord) {
diff --git a/typo3/sysext/workspaces/Classes/Service/StagesService.php b/typo3/sysext/workspaces/Classes/Service/StagesService.php
index 6f21394c61df..1dfd0a75beb8 100644
--- a/typo3/sysext/workspaces/Classes/Service/StagesService.php
+++ b/typo3/sysext/workspaces/Classes/Service/StagesService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -25,9 +27,6 @@
 use TYPO3\CMS\Workspaces\Domain\Record\StageRecord;
 use TYPO3\CMS\Workspaces\Domain\Record\WorkspaceRecord;
 
-/**
- * Stages service
- */
 class StagesService implements SingletonInterface
 {
     public const TABLE_STAGE = 'sys_workspace_stage';
@@ -37,26 +36,15 @@ class StagesService implements SingletonInterface
     public const STAGE_PUBLISH_ID = -10;
     public const STAGE_EDIT_ID = 0;
 
-    /**
-     * Path to the locallang file
-     *
-     * @var string
-     */
-    private $pathToLocallang = 'LLL:EXT:workspaces/Resources/Private/Language/locallang.xlf';
+    private string $pathToLocallang = 'LLL:EXT:workspaces/Resources/Private/Language/locallang.xlf';
 
     protected ?RecordService $recordService;
 
     /**
      * Local cache to reduce number of database queries for stages, groups, etc.
-     *
-     * @var array
-     */
-    protected $workspaceStageCache = [];
-
-    /**
-     * @var array
      */
-    protected $workspaceStageAllowedCache = [];
+    protected array $workspaceStageCache = [];
+    protected array $workspaceStageAllowedCache = [];
 
     /**
      * Getter for current workspace id
@@ -69,13 +57,12 @@ public function getWorkspaceId(): int
     /**
      * Find the highest possible "previous" stage for all $byTableName
      *
-     * @param array $workspaceItems
      * @return array Current and next highest possible stage
      */
     public function getPreviousStageForElementCollection(
-        $workspaceItems,
+        array $workspaceItems,
         array $byTableName = ['tt_content', 'pages']
-    ) {
+    ): array {
         $currentStage = [];
         $previousStage = [];
         $usedStages = [];
@@ -116,13 +103,12 @@ public function getPreviousStageForElementCollection(
     /**
      * Retrieve the next stage based on the lowest stage given in the $workspaceItems record array.
      *
-     * @param array $workspaceItems
      * @return array Current and next possible stage.
      */
     public function getNextStageForElementCollection(
-        $workspaceItems,
+        array $workspaceItems,
         array $byTableName = ['tt_content', 'pages']
-    ) {
+    ): array {
         $currentStage = [];
         $usedStages = [];
         $nextStage = [];
@@ -165,7 +151,7 @@ public function getNextStageForElementCollection(
      *
      * @return array id and title of the stages
      */
-    public function getStagesForWS()
+    public function getStagesForWS(): array
     {
         if (isset($this->workspaceStageCache[$this->getWorkspaceId()])) {
             $stages = $this->workspaceStageCache[$this->getWorkspaceId()];
@@ -183,7 +169,7 @@ public function getStagesForWS()
      *
      * @return array id and title of stages
      */
-    public function getStagesForWSUser()
+    public function getStagesForWSUser(): array
     {
         if ($this->getBackendUser()->isAdmin()) {
             return $this->getStagesForWS();
@@ -226,9 +212,8 @@ public function getStagesForWSUser()
      * Prepares simplified stages array
      *
      * @param StageRecord[] $stageRecords
-     * @return array
      */
-    protected function prepareStagesArray(array $stageRecords)
+    protected function prepareStagesArray(array $stageRecords): array
     {
         $stagesArray = [];
         foreach ($stageRecords as $stageRecord) {
@@ -247,14 +232,11 @@ protected function prepareStagesArray(array $stageRecords)
     }
 
     /**
-     * Gets the title of a stage.
-     *
-     * @param int $ver_stage
-     * @return string
+     * Gets the title of a stage
      */
-    public function getStageTitle($ver_stage)
+    public function getStageTitle(int $stageId): string
     {
-        switch ($ver_stage) {
+        switch ($stageId) {
             case self::STAGE_PUBLISH_EXECUTE_ID:
                 $stageTitle = $this->getLanguageService()->sL('LLL:EXT:workspaces/Resources/Private/Language/locallang_mod_user_ws.xlf:stage_publish');
                 break;
@@ -265,8 +247,8 @@ public function getStageTitle($ver_stage)
                 $stageTitle = $this->getLanguageService()->sL('LLL:EXT:workspaces/Resources/Private/Language/locallang_mod_user_ws.xlf:stage_editing');
                 break;
             default:
-                $stageTitle = $this->getPropertyOfCurrentWorkspaceStage($ver_stage, 'title');
-                if ($stageTitle == null) {
+                $stageTitle = $this->getPropertyOfCurrentWorkspaceStage($stageId, 'title');
+                if ($stageTitle === null) {
                     $stageTitle = $this->getLanguageService()->sL('LLL:EXT:workspaces/Resources/Private/Language/locallang.xlf:error.getStageTitle.stageNotFound');
                 }
         }
@@ -275,13 +257,10 @@ public function getStageTitle($ver_stage)
 
     /**
      * Gets a particular stage record.
-     *
-     * @param int $stageid
-     * @return array|null
      */
-    public function getStageRecord($stageid)
+    public function getStageRecord(int $stageId): ?array
     {
-        return BackendUtility::getRecord('sys_workspace_stage', $stageid);
+        return BackendUtility::getRecord('sys_workspace_stage', $stageId);
     }
 
     /**
@@ -289,9 +268,8 @@ public function getStageRecord($stageid)
      *
      * @param int $stageId Id of the stage to fetch the next one for
      * @return array The next stage (id + details)
-     * @throws \InvalidArgumentException
      */
-    public function getNextStage($stageId)
+    public function getNextStage(int $stageId): array
     {
         if (!MathUtility::canBeInterpretedAsInteger($stageId)) {
             throw new \InvalidArgumentException(
@@ -331,7 +309,7 @@ public function getNextStage($stageId)
      * @param int $stageId Current stage id of the record
      * @return array Next stages
      */
-    public function getNextStages(array &$nextStageArray, $stageId)
+    protected function getNextStages(array &$nextStageArray, int $stageId): array
     {
         // Current stage is "Ready to publish" - there is no next stage
         if ($stageId == self::STAGE_PUBLISH_ID) {
@@ -357,10 +335,9 @@ public function getNextStages(array &$nextStageArray, $stageId)
      * Get next stage in process for given stage id
      *
      * @param int $stageId Id of the stage to fetch the previous one for
-     * @return bool|array The previous stage or false
-     * @throws \InvalidArgumentException
+     * @return false|array The previous stage or false
      */
-    public function getPrevStage($stageId)
+    public function getPrevStage(int $stageId): false|array
     {
         if (!MathUtility::canBeInterpretedAsInteger($stageId)) {
             throw new \InvalidArgumentException(
@@ -392,7 +369,7 @@ public function getPrevStage($stageId)
      * @param int $stageId Current stage id of the record
      * @return array prev stages
      */
-    public function getPrevStages(array &$prevStageArray, $stageId)
+    protected function getPrevStages(array &$prevStageArray, int $stageId): array
     {
         // Current stage is "Editing" - there is no prev stage
         if ($stageId != self::STAGE_EDIT_ID) {
@@ -414,11 +391,10 @@ public function getPrevStages(array &$prevStageArray, $stageId)
      * Gets all backend user records that are considered to be responsible
      * for a particular stage or workspace.
      *
-     * @param StageRecord|int $stageRecord Stage
      * @param bool $selectDefaultUserField If field notification_defaults should be selected instead of responsible users
      * @return array be_users with e-mail and name
      */
-    public function getResponsibleBeUser($stageRecord, $selectDefaultUserField = false)
+    public function getResponsibleBeUser(StageRecord|int $stageRecord, bool $selectDefaultUserField = false): array
     {
         if (!$stageRecord instanceof StageRecord) {
             $stageRecord = $this->getWorkspaceRecord()->getStage($stageRecord);
@@ -443,11 +419,8 @@ public function getResponsibleBeUser($stageRecord, $selectDefaultUserField = fal
     /**
      * Resolves backend user ids from a mixed list of backend users
      * and backend user groups (e.g. "be_users_1,be_groups_3,be_users_4,...")
-     *
-     * @param string $backendUserGroupList
-     * @return array
      */
-    public function resolveBackendUserIds($backendUserGroupList)
+    public function resolveBackendUserIds(string $backendUserGroupList): array
     {
         $elements = GeneralUtility::trimExplode(',', $backendUserGroupList, true);
         $backendUserIds = [];
@@ -477,32 +450,21 @@ public function resolveBackendUserIds($backendUserGroupList)
 
     /**
      * Gets backend user records from a given list of ids.
-     *
-     * @param string $backendUserList
-     * @return array
      */
-    public function getBackendUsers($backendUserList)
+    public function getBackendUsers(string $backendUserList): array
     {
         if (empty($backendUserList)) {
             return [];
         }
 
         $backendUserList = implode(',', GeneralUtility::intExplode(',', $backendUserList));
-        $backendUsers = BackendUtility::getUserNames(
+        return BackendUtility::getUserNames(
             'username, uid, email, realName, lang, uc',
             'AND uid IN (' . $backendUserList . ')' . BackendUtility::BEenableFields('be_users')
         );
-
-        if (empty($backendUsers)) {
-            $backendUsers = [];
-        }
-        return $backendUsers;
     }
 
-    /**
-     * @return array
-     */
-    public function getPreselectedRecipients(StageRecord $stageRecord)
+    public function getPreselectedRecipients(StageRecord $stageRecord): array
     {
         if ($stageRecord->areEditorsPreselected()) {
             return array_merge(
@@ -513,23 +475,15 @@ public function getPreselectedRecipients(StageRecord $stageRecord)
         return $stageRecord->getPreselectedRecipients();
     }
 
-    /**
-     * @return WorkspaceRecord
-     */
-    protected function getWorkspaceRecord()
+    protected function getWorkspaceRecord(): WorkspaceRecord
     {
         return WorkspaceRecord::get($this->getWorkspaceId());
     }
 
     /**
      * Gets a property of a workspaces stage.
-     *
-     * @param int $stageId
-     * @param string $property
-     * @return string
-     * @throws \InvalidArgumentException
      */
-    public function getPropertyOfCurrentWorkspaceStage($stageId, $property)
+    public function getPropertyOfCurrentWorkspaceStage(int $stageId, string $property): ?string
     {
         $result = null;
         if (!MathUtility::canBeInterpretedAsInteger($stageId)) {
@@ -549,10 +503,9 @@ public function getPropertyOfCurrentWorkspaceStage($stageId, $property)
      * Gets the position of the given workspace in the hole process
      * f.e. 3 means step 3 of 20, by which 1 is edit and 20 is ready to publish
      *
-     * @param int $stageId
      * @return array position => 3, count => 20
      */
-    public function getPositionOfCurrentStage($stageId)
+    public function getPositionOfCurrentStage(int $stageId): array
     {
         $stagesOfWS = $this->getStagesForWS();
         $countOfStages = count($stagesOfWS);
@@ -577,11 +530,8 @@ public function getPositionOfCurrentStage($stageId)
 
     /**
      * Check if the user has access to the previous stage, relative to the given stage
-     *
-     * @param int $stageId
-     * @return bool
      */
-    public function isPrevStageAllowedForUser($stageId)
+    public function isPrevStageAllowedForUser(int $stageId): bool
     {
         $isAllowed = false;
         try {
@@ -599,11 +549,8 @@ public function isPrevStageAllowedForUser($stageId)
 
     /**
      * Check if the user has access to the next stage, relative to the given stage
-     *
-     * @param int $stageId
-     * @return bool
      */
-    public function isNextStageAllowedForUser($stageId)
+    public function isNextStageAllowedForUser(int $stageId): bool
     {
         $isAllowed = false;
         try {
@@ -619,11 +566,7 @@ public function isNextStageAllowedForUser($stageId)
         return $isAllowed;
     }
 
-    /**
-     * @param int $stageId
-     * @return bool
-     */
-    protected function isStageAllowedForUser($stageId)
+    protected function isStageAllowedForUser(int $stageId): bool
     {
         $cacheKey = $this->getWorkspaceId() . '_' . $stageId;
         if (isset($this->workspaceStageAllowedCache[$cacheKey])) {
@@ -635,12 +578,9 @@ protected function isStageAllowedForUser($stageId)
     }
 
     /**
-     * Determines whether a stage Id is valid.
-     *
-     * @param int $stageId The stage Id to be checked
-     * @return bool
+     * Determines whether a stageId is valid.
      */
-    public function isValid($stageId)
+    public function isValid(int $stageId): bool
     {
         $isValid = false;
         $stages = $this->getStagesForWS();
@@ -653,10 +593,7 @@ public function isValid($stageId)
         return $isValid;
     }
 
-    /**
-     * @return RecordService
-     */
-    public function getRecordService()
+    public function getRecordService(): RecordService
     {
         if (!isset($this->recordService)) {
             $this->recordService = GeneralUtility::makeInstance(RecordService::class);
diff --git a/typo3/sysext/workspaces/Classes/Service/WorkspaceService.php b/typo3/sysext/workspaces/Classes/Service/WorkspaceService.php
index 3e1e336401c7..54ebd168a662 100644
--- a/typo3/sysext/workspaces/Classes/Service/WorkspaceService.php
+++ b/typo3/sysext/workspaces/Classes/Service/WorkspaceService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the TYPO3 CMS project.
  *
@@ -29,31 +31,21 @@
 use TYPO3\CMS\Core\Utility\MathUtility;
 use TYPO3\CMS\Core\Versioning\VersionState;
 
-/**
- * Workspace service
- */
 class WorkspaceService implements SingletonInterface
 {
-    /**
-     * @var array
-     */
-    protected $versionsOnPageCache = [];
-
-    /**
-     * @var array
-     */
-    protected $pagesWithVersionsInTable = [];
+    protected array $versionsOnPageCache = [];
+    protected array $pagesWithVersionsInTable = [];
 
     public const TABLE_WORKSPACE = 'sys_workspace';
     public const LIVE_WORKSPACE_ID = 0;
 
     /**
-     * retrieves the available workspaces from the database and checks whether
+     * Retrieves the available workspaces from the database and checks whether
      * they're available to the current BE user
      *
      * @return array array of workspaces available to the current user
      */
-    public function getAvailableWorkspaces()
+    public function getAvailableWorkspaces(): array
     {
         $backendUser = $this->getBackendUser();
         $availableWorkspaces = [];
@@ -113,8 +105,6 @@ public function getPreviewLinkLifetime(): int
 
     /**
      * Find the title for the requested workspace.
-     *
-     * @throws \InvalidArgumentException
      */
     public function getWorkspaceTitle(int $wsId): string
     {
@@ -140,14 +130,12 @@ public function getWorkspaceTitle(int $wsId): string
      * Building DataHandler CMD-array for publishing all versions in a workspace.
      *
      * @param int $wsid Real workspace ID, cannot be ONLINE (zero).
-     * @param bool $_ Unused, previously used to choose between swapping and publishing
-     * @param int $pageId The page id
+     * @param bool $_ Dummy parameter, only there because testing framework is calling it with 2 parameters
      * @param int|null $language Select specific language only
      * @return array Command array for DataHandler
      */
-    public function getCmdArrayForPublishWS($wsid, $_ = false, $pageId = 0, $language = null)
+    public function getCmdArrayForPublishWS(int $wsid, bool $_ = false, int $language = null): array
     {
-        $wsid = (int)$wsid;
         $cmd = [];
         if ($wsid > 0) {
             // Define stage to select:
@@ -160,7 +148,7 @@ public function getCmdArrayForPublishWS($wsid, $_ = false, $pageId = 0, $languag
             $versions = $this->selectVersionsInWorkspace(
                 $wsid,
                 $stage,
-                $pageId ?: -1,
+                -1,
                 999,
                 'tables_modify',
                 $language
@@ -181,14 +169,11 @@ public function getCmdArrayForPublishWS($wsid, $_ = false, $pageId = 0, $languag
      * Building DataHandler CMD-array for releasing all versions in a workspace.
      *
      * @param int $wsid Real workspace ID, cannot be ONLINE (zero).
-     * @param bool $flush Run Flush (TRUE) or ClearWSID (FALSE) command
-     * @param int $pageId The page id
-     * @param int $language Select specific language only
+     * @param int|null $language Select specific language only
      * @return array Command array for DataHandler
      */
-    public function getCmdArrayForFlushWS($wsid, $flush = true, $pageId = 0, $language = null)
+    public function getCmdArrayForFlushWS(int $wsid, int $language = null)
     {
-        $wsid = (int)$wsid;
         $cmd = [];
         if ($wsid > 0) {
             // Define stage to select:
@@ -197,7 +182,7 @@ public function getCmdArrayForFlushWS($wsid, $flush = true, $pageId = 0, $langua
             $versions = $this->selectVersionsInWorkspace(
                 $wsid,
                 $stage,
-                $pageId ?: -1,
+                -1,
                 999,
                 'tables_modify',
                 $language
@@ -205,8 +190,7 @@ public function getCmdArrayForFlushWS($wsid, $flush = true, $pageId = 0, $langua
             // Traverse the selection to build CMD array:
             foreach ($versions as $table => $records) {
                 foreach ($records as $rec) {
-                    // Build the cmd Array:
-                    $cmd[$table][$rec['uid']]['version'] = ['action' => $flush ? 'flush' : 'clearWSID'];
+                    $cmd[$table][$rec['uid']]['version'] = ['action' => 'flush'];
                 }
             }
         }
@@ -226,10 +210,9 @@ public function getCmdArrayForFlushWS($wsid, $flush = true, $pageId = 0, $langua
      * @param int $language Select specific language only
      * @return array Array of all records uids etc. First key is table name, second key incremental integer. Records are associative arrays with uid and t3ver_oidfields. The pid of the online record is found as "livepid" the pid of the offline record is found in "wspid
      */
-    public function selectVersionsInWorkspace($wsid, $stage = -99, $pageId = -1, $recursionLevel = 0, $selectionType = 'tables_select', $language = null)
+    public function selectVersionsInWorkspace(int $wsid, int $stage = -99, int $pageId = -1, int $recursionLevel = 0, string $selectionType = 'tables_select', int $language = null): array
     {
         $backendUser = $this->getBackendUser();
-        $wsid = (int)$wsid;
         $output = [];
         // Contains either nothing or a list with live-uids
         if ($pageId != -1 && $recursionLevel > 0) {
@@ -258,7 +241,7 @@ public function selectVersionsInWorkspace($wsid, $stage = -99, $pageId = -1, $re
             }
             if (BackendUtility::isTableWorkspaceEnabled($table)) {
                 $recs = $this->selectAllVersionsFromPages($table, $pageList, $wsid, $stage, $language);
-                $newRecords = $this->getNewVersionsForPages($table, $pageList, $wsid, (int)$stage, $language);
+                $newRecords = $this->getNewVersionsForPages($table, $pageList, $wsid, $stage, $language);
                 foreach ($newRecords as &$newRecord) {
                     // If we're dealing with a 'new' record, this one has no t3ver_oid. On publish, there is no
                     // live counterpart, but the publish methods later need a live uid to publish to. We thus
@@ -279,15 +262,8 @@ public function selectVersionsInWorkspace($wsid, $stage = -99, $pageId = -1, $re
 
     /**
      * Find all versionized elements except moved and new records.
-     *
-     * @param string $table
-     * @param string $pageList
-     * @param int $wsid
-     * @param int $stage
-     * @param int $language
-     * @return array
      */
-    protected function selectAllVersionsFromPages($table, $pageList, $wsid, $stage, $language = null)
+    protected function selectAllVersionsFromPages(string $table, string $pageList, int $wsid, int $stage, int $language = null): array
     {
         // Include root level page as there might be some records with where root level
         // restriction is ignored (e.g. FAL records)
@@ -517,14 +493,8 @@ protected function getNewVersionsForPages(
 
     /**
      * Find all moved records at their new position.
-     *
-     * @param string $table
-     * @param string $pageList
-     * @param int $wsid
-     * @param int $stage
-     * @return array
      */
-    protected function getMovedRecordsFromPages($table, $pageList, $wsid, $stage)
+    protected function getMovedRecordsFromPages(string $table, string $pageList, int $wsid, int $stage): array
     {
         $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable($table);
         $queryBuilder->getRestrictions()->removeAll()
@@ -621,12 +591,9 @@ protected function getMovedRecordsFromPages($table, $pageList, $wsid, $stage)
     /**
      * Find all page uids recursive starting from a specific page
      *
-     * @param int $pageId
-     * @param int $wsid
-     * @param int $recursionLevel
      * @return string Comma sep. uid list
      */
-    protected function getTreeUids($pageId, $wsid, $recursionLevel)
+    protected function getTreeUids(int $pageId, int $wsid, int $recursionLevel): string
     {
         $backendUser = $this->getBackendUser();
         // Reusing existing functionality with the drawback that
@@ -778,19 +745,13 @@ protected function getPageChildrenRecursive(int $pid, int $depth, int $begin, st
 
     /**
      * Remove all records which are not permitted for the user
-     *
-     * @param array $recs
-     * @param string $table
-     * @return array
      */
-    protected function filterPermittedElements($recs, $table)
+    protected function filterPermittedElements(array $recs, string $table): array
     {
         $permittedElements = [];
-        if (is_array($recs)) {
-            foreach ($recs as $rec) {
-                if ($this->isPageAccessibleForCurrentUser($table, $rec) && $this->isLanguageAccessibleForCurrentUser($table, $rec)) {
-                    $permittedElements[] = $rec;
-                }
+        foreach ($recs as $rec) {
+            if ($this->isPageAccessibleForCurrentUser($table, $rec) && $this->isLanguageAccessibleForCurrentUser($table, $rec)) {
+                $permittedElements[] = $rec;
             }
         }
         return $permittedElements;
@@ -801,9 +762,8 @@ protected function filterPermittedElements($recs, $table)
      *
      * @param string $table Name of the table
      * @param array $record Record row to be checked
-     * @return bool
      */
-    protected function isPageAccessibleForCurrentUser($table, array $record)
+    protected function isPageAccessibleForCurrentUser(string $table, array $record): bool
     {
         $pageIdField = $table === 'pages' ? 'uid' : 'wspid';
         $pageId = isset($record[$pageIdField]) ? (int)$record[$pageIdField] : null;
@@ -823,9 +783,8 @@ protected function isPageAccessibleForCurrentUser($table, array $record)
      *
      * @param string $table Name of the table
      * @param array $record Record row to be checked
-     * @return bool
      */
-    protected function isLanguageAccessibleForCurrentUser($table, array $record)
+    protected function isLanguageAccessibleForCurrentUser(string $table, array $record): bool
     {
         if (BackendUtility::isTableLocalizable($table)) {
             $languageUid = $record[$GLOBALS['TCA'][$table]['ctrl']['languageField']] ?? 0;
@@ -841,7 +800,7 @@ protected function isLanguageAccessibleForCurrentUser($table, array $record)
      * @param int $id Primary key of the page to check
      * @param int $language Language for which to check the page
      */
-    public function isNewPage($id, $language = 0): bool
+    public function isNewPage(int $id, int $language = 0): bool
     {
         $isNewPage = false;
         // If the language is not default, check state of overlay
@@ -890,9 +849,9 @@ public function isNewPage($id, $language = 0): bool
      * @param int $pageId
      * @return bool
      */
-    public function hasPageRecordVersions($workspaceId, $pageId)
+    public function hasPageRecordVersions(int $workspaceId, int $pageId): bool
     {
-        if ((int)$workspaceId === 0 || (int)$pageId === 0) {
+        if ($workspaceId === 0 || $pageId === 0) {
             return false;
         }
 
@@ -936,12 +895,8 @@ public function hasPageRecordVersions($workspaceId, $pageId)
      *     21 => true
      *   ],
      * ]
-     *
-     * @param int $workspaceId
-     *
-     * @return array
      */
-    public function getPagesWithVersionsInTable($workspaceId)
+    public function getPagesWithVersionsInTable(int $workspaceId): array
     {
         foreach ($GLOBALS['TCA'] as $tableName => $tableConfiguration) {
             if ($tableName === 'pages' || !BackendUtility::isTableWorkspaceEnabled($tableName)) {
@@ -964,12 +919,8 @@ public function getPagesWithVersionsInTable($workspaceId)
      *   13 => true,
      *   15 => true
      * ],
-     *
-     * @param int $workspaceId
-     * @param string $tableName
-     * @return array
      */
-    protected function fetchPagesWithVersionsInTable($workspaceId, $tableName)
+    protected function fetchPagesWithVersionsInTable(int $workspaceId, string $tableName): array
     {
         if ((int)$workspaceId === 0) {
             return [];