public Set<MessageGid> generateRandomDeps()
	{
		Random rand = new Random();

		MessageGid[] msg_gid_array = (MessageGid[]) this.mid_ts_map.keySet().toArray(new MessageGid[mid_ts_map.size()]);
		int size = msg_gid_array.length;

		HashSet<MessageGid> msg_gid_set = new HashSet<>();
		if (size > 0)
		{
			int start = rand.nextInt(size);
			int end = rand.nextInt(size);
			if (start < end)
				for (int index = start; index < end; index++) 
					msg_gid_set.add(msg_gid_array[index]);
			else
				for (int index = end; index < start; index++)
					msg_gid_set.add(msg_gid_array[index]);
		}
		
		return msg_gid_set;
	}