Formatting a Java file sometimes eats parts of the code

This is similar to a bug that existed in Eclipse maybe 5 or 10 years ago.

Every now and then when you press format, part of the code is deleted. This is really super bad for any IDE, especially when you have auto format on save turned on. "Done with your changes? Sure, let me just save and commit. Why did you commit broken code, it doesn't even compile? %#€""

It seems like the formatter and also code highlighting gets out of sync with reality when this happens, e.g. in this example you can see that return is incorrectly colored.

https://user-images.githubusercontent.com/260340/138037841-aabf6088-d086-41f0-9908-98e3ec7eb555.mov

Environment

• Operating System: mac os Big Sur
• JDK version: 17
• Visual Studio Code version: 1.61.1
• Java extension version: 0.82.0

Steps To Reproduce

1. Use VS Code until it happens... there is no reliable way as far as I know

Start with the supplied recording and the formatter and code-highlighting behavior described in the issue, using the listed macOS, JDK 17, VS Code 1.61.1, and Java extension 0.82.0 environment. Reproduce the intermittent failure or narrow down triggering conditions, then verify that formatting no longer deletes code and that highlighting remains synchronized.