[TxMt] How to unbind ^J from "Reformat and Justify"

[Kenneth McDonald]

I'd like to use this key binding for something else, but I can't find 
the TextMate default binding for ^J anywhere to unbind it; not in a 
bundle, and not in the System's Keyboard Preferences binding list.

In general, is there an easy way to find out where a particular 
keybinding is set?

Thanks,
Ken