public GScheduledTask addTask(GTask task, int priority) {
		if (scheduled) {
			throw new IllegalStateException("Can't directly add new tasks on a group that has "
				+ "been scheduled with a GTaskManager");
		}
		return doAddTask(task, priority);
	}
Add a task to this group with the given priority.  Tasks can only be added to this group
before the group is added to the GTaskManager.  After that, an IllegalStateException will
be thrown.
@param task the task being added to this group.
@param priority the priority for the task within the group.
@return the GScheduledTask created to schedule this task within the group.
@throws IllegalStateException if this method is called after the group has been added to
the GTaskManager.
Ghidra/Framework/Project/src/main/java/ghidra/framework/task/GTaskGroup.java