public function isRequired($field)
    {
        $parts = explode('.', $field);
        $entity = $this->entity($parts);

        $isNew = true;
        if ($entity instanceof EntityInterface) {
            $isNew = $entity->isNew();
        }

        $validator = $this->_getValidator($parts);
        $fieldName = array_pop($parts);
        if (!$validator->hasField($fieldName)) {
            return false;
        }
        if ($this->type($field) !== 'boolean') {
            return $validator->isEmptyAllowed($fieldName, $isNew) === false;
        }

        return false;
    }