Fix 🦶🔫: Validate visitNonNull arguments

[JLLeitschuh]

I often find myself shooting myself in the foot passing the wrong Cursor to visitNonNull.

This is a very easy mistake to make and often leads to quite a bit of confusion.

This fixes that by validating that a parent cursor is being passed, not the current cursor.

Signed-off-by: Jonathan Leitschuh [email protected]

What's changed?

Adds a bit of sanity validation to visitNonNull(Tree tree, P p, Cursor parent)

AFAIK this method is really only called when composing one visitor of another visitor, and
isn't called in the hot-path for normal LST tree traversal.

What's your motivation?

Reduce how often I and other's new to OpenRewrite make the mistake of passing the Cursor for the tree, instead of passing the parent cursor.

Anything in particular you'd like reviewers to focus on?

Anyone you would like to review specifically?

Have you considered any alternatives or workarounds?

Any additional context

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files

[JLLeitschuh]

@sambsnyd want to take a look at this too?