How to attach JavaDoc .jar for library .jar and get editor to show the documentation?

From @mattflix on February 23, 2019 19:58

I have tried various techniques to specify the JavaDoc .jar that should be attached to a given library .jar (that appears in the "Referenced Libraries" section of the "JAVA DEPENDENCIES" view, and is successfully used by my app), but nothing has worked.

Currently, the only JavaDoc documentation that appears in the editor for me is that for the built-in objects/members, like Object and toString(). No third-party libraries seem to have any JavaDoc exposed in the editor.

Is there any example of a simple project configured with a dependency on a library .jar (that has an associated JavaDoc .jar, also located on the local file system) where the editor is able to display the documentation comments for selected Java types and members?

Copied from original issue: Microsoft/vscode-java-pack#105

ファイル、テスト、エントリポイントのいずれも指定されていません。ローカルライブラリ .jar と関連する JavaDoc .jar を使って単純なプロジェクトを再現し、エディターでサードパーティ製 Java の型とメンバーのドキュメントが表示されるかを確認してください。文書化された動作する構成、または確認済みの不具合が得られれば完了です。