public void addTaskListener(TaskListener listener) {
		if (listener != null) {
			listeners.add(listener);
		}
	}
Sets the task listener on this task.  It is a programming error to call this method more
than once or to call this method if a listener was passed into the constructor of this class.
@param listener the listener
Ghidra/Framework/Gui/src/main/java/ghidra/util/task/Task.java