First of all, you should post a discussion, not a document for your questions. Spark is not developed by JiveSoftware anymore. It is a product of IgniteRealtime.org community. Spark is under Apache License. I’m not a laywer, but his an excerpt from wikipedia:
The Apache License is considered permissive in that it does not require modified versions of the software to be distributed using the same license (unlike copyleft licenses - see comparison). In every licensed file, any original copyright, patent, trademark, and attribution notices in redistributed code must be preserved (excluding notices that do not pertain to any part of the derivative works); and, in every licensed file changed, a notification must be added stating that changes have been made to that file.
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