Jabit is a Bitmessage library for the Java environment, written in Kotlin. It is used by both Abit and Jabit-Server, and it shouldn’t be too hard to create your own Bitmessage client with it.
This is a simple Bitmessage server application made with Jabit. It can be used as a trusted node for the Abit, both for simple synchronization and ‘server proof-of-work’.