synchronized public void checkCancelled(TaskMonitor monitor) throws CancelledException {
		if (cancelled) {
			throw new CancelledException();
		}
		if (monitor.isCancelled()) {
			monitor.setMessage("Cancelled Finding Differences");
			cancelled = true;
			throw new CancelledException();
		}
	}
Checks the task associated with the indicated monitor to determine if it has
been canceled.
@param monitor the task monitor, associated with getting differences from this Diff,
to be checked
@throws CancelledException if the getDifferences() task has been canceled by the user.
Ghidra/Features/Base/src/main/java/ghidra/program/util/ProgramDiff.java