/**
  * {@inheritdoc}
  */
 protected function getRequired()
 {
     return array_merge(parent::getRequired(), [self::CONFIG_USERNAME => '', self::CONFIG_PASSWORD => '']);
 }
 /**
  * @inheritdoc
  */
 protected function getRequired()
 {
     return array_merge(parent::getRequired(), ['username', 'password']);
 }
 /**
  * {@inheritdoc}
  */
 protected function getRequired()
 {
     return array_merge(parent::getRequired(), [self::CONFIG_CODE => '']);
 }
 /**
  * @inheritdoc
  */
 protected function getRequired()
 {
     return array_merge(parent::getRequired(), ['code']);
 }