Fix signature mismatch error.

src/Datasource/Query.php

@@ -7,6 +7,7 @@
 use Cake\Datasource\Exception\RecordNotFoundException;
 use Cake\Datasource\QueryInterface;
 use Cake\Datasource\QueryTrait;
+use Cake\Datasource\ResultSetInterface;
 use Cake\Utility\Hash;
 use InvalidArgumentException;
 use IteratorAggregate;
@@ -535,17 +536,19 @@ public function triggerBeforeFind()
      */
     public function execute()
     {
-        return $this->_execute();
+        if ($this->clause('action') === self::ACTION_READ) {
+            return $this->_execute();
+        }
+
+        return $this->__resultSet = $this->_webservice->execute($this);
     }
 
     /**
      * Executes this query and returns a traversable object containing the results
      *
-     * @return bool|int|\Cake\Datasource\ResultSetInterface
-     * @psalm-suppress TraitMethodSignatureMismatch
-     * @psalm-suppress ImplementedReturnTypeMismatch
+     * @return \Cake\Datasource\ResultSetInterface
      */
-    protected function _execute()
+    protected function _execute(): ResultSetInterface
     {
         $this->triggerBeforeFind();
         if ($this->__resultSet) {

tests/TestCase/QueryTest.php

@@ -167,10 +167,11 @@ public function testExecuteTwice()
     {
         $mockWebservice = $this
             ->getMockBuilder('\TestApp\Webservice\StaticWebservice')
-            ->setMethods([
+            ->onlyMethods([
                 'execute',
             ])
             ->getMock();
+
         $mockWebservice->expects($this->once())
             ->method('execute')
             ->will($this->returnValue(new ResultSet([
@@ -187,7 +188,10 @@ public function testExecuteTwice()
                     'title' => 'Webservices',
                 ]),
             ], 3)));
-        $this->query->setWebservice($mockWebservice);
+
+        $this->query
+            ->setWebservice($mockWebservice)
+            ->action(Query::ACTION_READ);
 
         $this->query->execute();