Fail to Preview and Refactor with deleting parameters in Change Method Signature window

[yuyully]

Environment

• Operating System: Mac
• JDK version: 17.0.6
• Visual Studio Code version: 1.77.3
• Java extension version: 1.18.0

Steps To Reproduce

1. In a method which contains two parameters > Change signature from quick action
2. In Change Method Signature window, delete one parameter > Preview or Refactor

Current Result

Expected Result

Can preview and refactor successfully.

[yuyully]

• Change Method Signature > Go to Exception tab > Same behavior while deleting existing exceptions.
• Change Method Signature > Go to Exception tab > Add an exception with default name > Refactor (succeed) > Add an exception with default name again, Refactor and Preview don't work without errors.

[rgrunber]

I just checked and eclipse-jdtls/eclipse.jdt.ls#2754 should solve all of these, except the "adding an exception with a default name again". If by default name you mean "Exception"/"java.lang.Exception", while it doesn't appear to be a compilation error, it doesn't really make sense to have public void someMethod () throws Exception, Exception. The refactoring is partly correct in pointing out that you haven't really changed anything, although I guess the signature is technically different ?

We could improve this in the future if there really is a case for it.

The latter is actually an upstream issue we'd have to fix in the signature processor because even in Eclipse itself it doesn't permit adding a duplicate :

[rgrunber]

I would close this for now as the really annoying aspects of this issue ("change signature" doing downright strange things) should be resolved now.