Hi there 
This dude gave a talk about OCaml-Java, while the Github repo and the webpage - both maintained by him - are outdated since years.
What is this about?
I already send him an Email on the address given in the mentioned webpage.
Are you interested?
Well, yeah! If anyone out there is working on OCaml-Java interop, please speak up and give some hope to corporate cogs everywhere!
Being able to run OCaml on the jvm with a good interop interface would be a good thing imo. There are Java libraries that will never exist as OCaml libs until Ocaml is as popular as Java, and for as long as Java. It would be nice to be able to use those libs from OCaml source. Even where there are simliar libs that can be called from OCaml native code, using them would often be trickier because the interface is at a lower level.
(Example: I write agent-basd simulations in Clojure using a Java ABM library. I would consider doing that in OCaml if there was a good ABM library that was easy to use from OCaml, but I don’t believe that’s likely. There’s a Javascript ABM lib I might try with Bucklescript or jsoo, but it’s more limited.)
I quote
It has been difficult to find time to work on it, but I started to update the underlying libraries to support the latest version of Java. I have used OCaml-Java in production for more than two years (to serve a REST API), and encountered no major problem. I will be glad to assist you if you encounter any problem. Regards, Xavier