In the latest JVB releases (some time after 519 and before 560) a new
jar appears in the lib directory. The 571 release has this one:
$ sha256sum callstats-0.0.1-20151106.175444-5.jar
It looks like source code is included, but the source files do not
indicate under which license they are released.
Can you help convince the author(s) to release the library under a Free
P.S. Maybe the code is already licensed this way but I could not find
evidence of it within the jar nor via web searches.