I have an interface which is now empty, and extends another interface. I'd like to remove the empty interface and use the base interface, and am trying to find the correct refactoring in IntelliJ.
I've tried "remove middleman" but got "cannot perform the refactoring. The caret should be positioned at the name of the field to be refactored".
I think that what you're looking for is the "Type Migration" refactoring.
Looking at a blog post explaining the "Remove Middleman" refactoring in IDEA, I'd think you simply cannot use it for this. It's just for "replacing all calls to delegating methods with the equivalent direct calls".
(For a moment I thought another refactoring, "Use Interface Where Possible", might be of help, but I couldn't get that working either in my simple test case.)