Formatter deletes a newline after content assist invocation

This has been occurring for a while now, but I've not been able to record it. Every time it occurs, when I retry the same steps, its not reproducible.

I don't have clear reproduction steps, but it seems to occur e.g. when I start Eclipse in my workspace and edit: `org.eclipse.e4.ui.tests.workbench.PartOnTopManagerTest.test_PlaceholderOnTopStackSwitch()`

I'm writing `if (System.getenv`, invoking content assist and an unexpected newline appears. See screen recording:

https://github.com/user-attachments/assets/9e347225-d07a-4df0-bee7-d5699c08e8cc

The screen recording is missing the content assist pop-up with options for `System.getenv()` and `System.getenv(String)`, I'm selecting the 2nd option (with the `String` argument). I'm only using the keyboard here, no mouse.