We use an outdated version of JCraft's jsch (v0.1.51 of March 2014). There is a newer one (v0.1.55 of November 2018).
However, that version still does not support current signature algorithms and there is the possibility that connecting to some servers may fail in future (cf. the future of jsch without ssh-rsa).
There is a fork of jsch that seems to be actively maintained and that includes recent algorithm additions: Fork of JSch-0.1.55. That fork should be source compatible with JCraft's jsch v0.1.51 that we currently use.