We don't expect Lightstreamer Server to be used as a dependency in a building project.
We only expect the Java In-Process Adapters SDK jar to be used to build java Adapters.
This jar (named like ls-adapter-inprocess-x.y.z.jar) is included in the Server package, but it is also available on Maven.
Obviously, you should search on Maven the same jar version included in the Server version in use.
If you are doing anything different, please expand.