/**
  * Validate default tree
  *
  * @param User       $user
  * @param Constraint $constraint
  */
 protected function validateDefaultTree($user, Constraint $constraint)
 {
     if (is_callable(array($user, 'getDefaultTree'))) {
         $tree = $user->getDefaultTree();
         if (!$tree) {
             $this->context->addViolation($constraint->missingTreeMessage);
         } elseif (!$tree->isRoot()) {
             $this->context->addViolation($constraint->invalidTreeMessage);
         }
     }
 }