synchronized void cancel() {
		isCancelled = true;
		runManager.cancelAllRunnables();
		if (currentIndex < mergeResolvers.length) {
			mergeResolvers[currentIndex].cancel();
		}
		notify();
	}
Called from the dialog when the "Cancel" button is hit; call the 
current MergeResolver's cancel() method, and wake up the merge
thread waiting on user input.
Ghidra/Features/Base/src/main/java/ghidra/app/merge/MergeManager.java