minor #12745 [Validator] Added a deprecation note about setPropertyAccessor #12698 (MICKtheBIG)

This PR was squashed before being merged into the 2.7 branch (closes #12745).

Discussion
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[Validator] Added a deprecation note about setPropertyAccessor #12698

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #12698
| License       | MIT
| Doc PR        |

Commits
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c82dc5e [Validator] Added a deprecation note about setPropertyAccessor #12698

Author: fabpot

ValidatorBuilder.php

@@ -301,9 +301,13 @@ public function setTranslationDomain($translationDomain)
 
     /**
      * {@inheritdoc}
+     *
+     * @deprecated Deprecated since version 2.5 and will be removed in 3.0. The validator will function without a property accessor.
      */
     public function setPropertyAccessor(PropertyAccessorInterface $propertyAccessor)
     {
+        trigger_error('ValidatorBuilder::setPropertyAccessor() is deprecated since version 2.5 and will be removed in 3.0. The validator will function without a property accessor.', E_USER_DEPRECATED);
+
         if (null !== $this->validatorFactory) {
             throw new ValidatorException('You cannot set a property accessor after setting a custom validator factory. Configure your validator factory instead.');
         }