Fix code style in string collection class
Fix code style in string collection class

spytz/yandex-php-library,AntonShevchuk/yandex-sdk-php,nixsolutions/yandex-php-library,loginwashere/yandex-php-library,nixsolutions/yandex-php-library,AntonShevchuk/yandex-sdk-php,spytz/yandex-php-library,loginwashere/yandex-php-library,zbarinov/yandex-php-library,zbarinov/yandex-php-library