private function validateAllRequired($isCreating) {
        foreach($this->getFiles() as $file) {
            if(!$file->isUsed()) {
                if($isCreating ? $file->isRequiredOnCreate() : $file->isRequiredOnUpdate()) {
                    $this->getEntity()->appendMessage(new Message('Missing the required file of: ' . $file->getName()));
                }
            }
        }
        if($this->getEntity()->validationHasFailed() == true) {
            $validationException = new ValidationException();
            $validationException->setEntity($this->getEntity());
            throw $validationException;
        }
    }