Commercial or Open Source Java Swing rule/predicate editor widget?

Question

Are there any commercial or open source Java Swing widgets that implement a rule/predicate editor UI? As an example of what I'm looking for, this image shows Cocoa's (excellent) NSPredicateEditor UI for editing a predicate expression:

Answer 1

I recently built something that does pretty much this for my application. It's somewhat application specific, but I think it should be possible to make it application agnostic. This is a screenshot of what I built:

In my scratching about, I didn't come across anything pre-built that would give me this "for free". But I could just be awful at finding such things.