Unable to load plugins in spark

I’m building the most recent version of spark and it’s throwing classdefnotfound error while loading the 2 plugins Phone and Jingle . I want to write code to remove this error but i don’t know what these plugins actually do. Do we have some source of documentation to which we refer while writing code ?
Any help would be appreciated !

Both plugins are mostly for audio calls (Phone uses SIP, Jingle uses, well, Jingle). I think Jingle can also be used for some other things (like video and file sharing), but i think it was added mostly for audio.

Related tickets:
https://issues.igniterealtime.org/browse/SPARK-1770
https://issues.igniterealtime.org/browse/SPARK-1892
https://issues.igniterealtime.org/browse/SPARK-1891
https://issues.igniterealtime.org/browse/SPARK-2065

There is no documentation other that included in the source (comments, todos, etc.).

@wroot I’m trying to go through precious versions . I’ve gone through every single version back till 2.5.8 and i get plugin errors in every build . Am i doing it right ?
Actually I’m trying to get involved in code but I’m unable to figure out start point. Can you give me a start . A small code change maybe . It’ll help me alot

Again, im not a developer, so i can’t tell whether you are doing something wrong and what exactly. I can share how im doing it with IntelliJ. Although I’m not building binaries, just running the source and i don’t import it, i use Github integration.