the java.trace.server configuration is an undocumented feature of VS Code. Formalizing its usage in vscode-java's package.json (similar to the HTML server) will prevent warnings in the VS Code settings file when it's used, as well as providing autocompletion for the supported values.

Supported values are:

• off : no trace
• messages : logs message types exchanged between VS Code and the java server
• verbose : logs JSON messages exchanged between VS Code and the java server