public function validationCustom(Validator $validator)
    {
        return $this->validationWidget($validator)
            ->requirePresence('body')
            ->add('body', [
                'notBlank' => [
                    'rule' => 'notBlank',
                    'message' => __d('block', "You need to provide a content for block's body."),
                ],
                'length' => [
                    'rule' => ['minLength', 3],
                    'message' => __d('block', "Block's body need to be at least 3 characters long."),
                ],
            ]);
    }