Overrides Constraint::ERROR_NAMES
protected const ERROR_NAMES = [ self::TOO_SHORT_ERROR => 'TOO_SHORT_ERROR', self::TOO_LONG_ERROR => 'TOO_LONG_ERROR', self::NOT_EQUAL_LENGTH_ERROR => 'NOT_EQUAL_LENGTH_ERROR', self::INVALID_CHARACTERS_ERROR => 'INVALID_CHARACTERS_ERROR', ];