Issue Description: Dynmap with Dynmap towny produces a ConcurrentModificationException which lags/crashes the server

• Dynmap Version: 3.3-beta-4
• Server Version: Paper 1.17.1
• Pastebin of Configuration.txt: https://pastebin.com/5SETL3z2
• Server Host (if applicable): selfhosted
• Pastebin of crashlogs or other relevant logs: https://pastebin.com/crashcausedbydynmap
• Steps to Replicate: Install dynmap and dynmap towny

[Yes] I have looked at all other issues and this is not a duplicate
[Yes] I have been able to replicate this

This is a known issue with dynmap addons that create markers (towny, worldgaurd, factions). What's new about this is it actually crashes the server.

is there any plan to fix?

Calls being made from off server thread aren't supported (and this looks to be an async task call) - never have been, since in general the Spigot/Paper API is not thread-safe from off of the server thread (with specific exceptions).

what can i do? dynmap towny dev says issue isn't with dynmap towny

paraphrased at best

am not trying to be rude i just dont know what to do

I had JsonFileClientUpdateComponent with disable-webserver set to true so i commented it out and works fine now