Fixed some more psalm issues.

src/Entity/Base/AbstractStructuralDBElement.php

@@ -254,6 +254,7 @@ abstract class AbstractStructuralDBElement extends AttachmentContainingDBElement
      * Get all sub elements of this element.
      *
      * @return Collection<static>|iterable all subelements as an array of objects (sorted by their full path)
+     * @psalm-return Collection<int, static>
      */
     public function getSubelements(): iterable
     {
@@ -262,6 +263,7 @@ abstract class AbstractStructuralDBElement extends AttachmentContainingDBElement
 
     /**
      * @return Collection<static>|iterable
+     * @psalm-return Collection<int, static>
      */
     public function getChildren(): iterable
     {

src/Entity/Parameters/ParametersTrait.php

@@ -31,7 +31,7 @@ trait ParametersTrait
     /**
      * Mapping done in subclasses.
      *
-     * @var Collection<AbstractParameter>
+     * @var Collection<int, AbstractParameter>
      * @Assert\Valid()
      */
     protected $parameters;
@@ -39,9 +39,9 @@ trait ParametersTrait
     /**
      *  Return all associated specifications.
      *
-     * @return \Doctrine\Common\Collections\Collection
+     * @return Collection
      *
-     * @psalm-return \Doctrine\Common\Collections\Collection<int, PartParameter>
+     * @psalm-return Collection<int, PartParameter>
      */
     public function getParameters(): \Doctrine\Common\Collections\Collection
     {