/**
  * Checks if current workflow item allows transition
  *
  * @param WorkflowData $value
  * @param TransitionIsAllowed $constraint
  */
 public function validate($value, Constraint $constraint)
 {
     /** @var WorkflowItem $workflowItem */
     $workflowItem = $constraint->getWorkflowItem();
     $transitionName = $constraint->getTransitionName();
     $workflow = $this->registry->getWorkflow($workflowItem->getWorkflowName());
     $errors = new ArrayCollection();
     $result = false;
     try {
         $result = $workflow->isTransitionAllowed($workflowItem, $transitionName, $errors, true);
     } catch (InvalidTransitionException $e) {
         switch ($e->getCode()) {
             case InvalidTransitionException::UNKNOWN_TRANSITION:
                 $errors->add(array('message' => $constraint->unknownTransitionMessage, 'parameters' => array('{{ transition }}' => $transitionName)));
                 break;
             case InvalidTransitionException::NOT_START_TRANSITION:
                 $errors->add(array('message' => $constraint->notStartTransitionMessage, 'parameters' => array('{{ transition }}' => $transitionName)));
                 break;
             case InvalidTransitionException::STEP_HAS_NO_ALLOWED_TRANSITION:
                 $errors->add(array('message' => $constraint->stepHasNotAllowedTransitionMessage, 'parameters' => array('{{ transition }}' => $transitionName, '{{ step }}' => $workflowItem->getCurrentStep()->getName())));
                 break;
         }
     }
     if (!$result) {
         if ($errors->count()) {
             foreach ($errors as $error) {
                 $this->context->addViolation($error['message'], $error['parameters']);
             }
         } else {
             $this->context->addViolation($constraint->someConditionsNotMetMessage);
         }
     }
 }