There are some features of the collectd 5 protocol that jcollectd lacks:
It would be helpful to have these in the jcollectd library as well.
I am also interested in see support for the collectd 5 protocol.
If I build it would you be open to adding ver 5 support into the main jcollectd code base?
I have experimental support for v5 working. I'll clean it up and submit a pull request. Not sure anyone still owns this project though.
I'm no longer active on this project or collectd, but I could arrange for push access to this repo if you're interested. I should also be able help transfer to another org if that would work better, under github.com/collectd maybe?