Issue #3453237: Added gitlab-ci file.

Closes #3453237

src/Plugin/Validation/Constraint/LinkAllowedHostConstraint.php

@@ -15,6 +15,11 @@ use Symfony\Component\Validator\Constraint;
  */
 class LinkAllowedHostConstraint extends Constraint {
 
+  /**
+   * The message to be displayed.
+   *
+   * @var string
+   */
   public $message = 'The host %host is forbidden. Only the following are allowed: %allowed_hosts.';
 
   /**