This is the home of the Language Server project docs.
There is a BazelCon presentation you can watch that covers the ideas. Start at the 12 minute mark to see the Language Server portion of the talk:
The Bazel Java Language Server (BJLS) is a plug-in for Eclipse, which extends the Eclipse Java Language Server with project import and classpath resolution capabilities for Bazel workspaces.
For more details about the supported Java features please see:
You cannot install the BJLS into VS Code. You have to install an extension for your editor/IDE bundling it.
We are working on integrating it directly into Language support for Java for Visual Studio Code. Until then please use Bazel support for Java for Visual Studio Code.