Blacklist zone by hands. This is the only working way so far. No plugin will do that for you in a good way.
Pathfinder issue is when your bot endlessly running in to the mountain, or wall, or in to the blaze in the middle of the city, because next path waypoint is inside that obstacle. What it does ) And this is much more fun than a group of mobs.
The bot will not avoid certain areas just because mobs are there. HMP's smart pull can at least avoid pulling groups if your bot tries to actively attack them.
But it doesn't stop the bot from pathing through groups. You will need to blacklist the general area and that way the pathfinder will *generally* try to avoid it - this isn't 100% reliable.
AvoidIt does this automatically and then forces the bot to generate a new path. It doesn't really work (well) which is why nothing like that has been implemented in the bot.
I've fixed compilation errors before and posted it in the vanilla section, but I'm pretty sure it's broken again now. Even when it "was working" - not reliable enough in any way.