Due to logstash' license, it maybe need to change the license from MIT to apache-2.0, so that we can use it from RubyGems.org
Logstash and all its plugins are licensed under Apache License, version 2 ("ALv2"). If you make your plugin publicly available via RubyGems.org, please make sure to have this line in your gemspec:
Due to logstash' license, it maybe need to change the license from MIT to apache-2.0, so that we can use it from RubyGems.org