Revert "Fix AbstractElement"

This reverts commit b6f8556.

models/Element/AbstractElement.php

@@ -132,7 +132,7 @@ public function getUserModification(): ?int
         return $this->userModification;
     }
 
-    public function setUserModification(?int $userModification): static
+    public function setUserModification(int $userModification): static
     {
         $this->markFieldDirty('userModification');
         $this->userModification = $userModification;
@@ -145,7 +145,7 @@ public function getCreationDate(): ?int
         return $this->creationDate;
     }
 
-    public function setCreationDate(?int $creationDate): static
+    public function setCreationDate(int $creationDate): static
     {
         $this->creationDate = $creationDate;
 
@@ -157,7 +157,7 @@ public function getModificationDate(): ?int
         return $this->modificationDate;
     }
 
-    public function setModificationDate(?int $modificationDate): static
+    public function setModificationDate(int $modificationDate): static
     {
         if($this->modificationDate != $modificationDate) {
             $this->markFieldDirty('modificationDate');
@@ -172,7 +172,7 @@ public function getUserOwner(): ?int
         return $this->userOwner;
     }
 
-    public function setUserOwner(?int $userOwner): static
+    public function setUserOwner(int $userOwner): static
     {
         $this->userOwner = $userOwner;