We are analyzing the possibility of using JRuby library for some maintenance tasks in a private closed-source application that we are selling to a customer.
According to the license information on their site https://github.com/jruby/jruby they use a triple license:
JRuby is licensed under a tri EPL/GPL/LGPL license. You can use it, redistribute it and/or modify it under the terms of the:
Eclipse Public License version 2.0 OR GNU General Public License version 2 OR GNU Lesser General Public License version 2.1
We are not modifying this library, and we only use it to run some maintenance scripts, so we do not think we should be considered a derivative project of any kind. As far as I know, if the license is LGPL we probably could use this library without providing the source code of our application (there would still be other obligations, such as mentioning this dependency, etc.).
But what does a triple-license mean? That I can choose which license I will be using? If so, can I use this library without opening our source code? Our customer strictly forbids this.