[TASK] Improve type annotations for AbstractValueObject

Resolves: #100142
Releases: main
Change-Id: I3981c16020eb2b210a40bedce89d8050bd2a851c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78094


Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Tested-by: Alexander Schnitzler <git@alexanderschnitzler.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/extbase/Classes/DomainObject/AbstractDomainObject.php

@@ -329,6 +329,9 @@ abstract class AbstractDomainObject implements DomainObjectInterface
         $this->_isClone = true;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function __toString(): string
     {
         return static::class . ':' . (string)$this->uid;

typo3/sysext/extbase/Classes/DomainObject/AbstractValueObject.php

@@ -25,9 +25,9 @@ abstract class AbstractValueObject extends AbstractDomainObject
     /**
      * Returns the value of the Value Object. Must be overwritten by a concrete value object.
      *
-     * @return string
+     * @return non-empty-string
      */
-    public function getValue()
+    public function getValue(): string
     {
         return $this->__toString();
     }