This commit changes the way MACreature initializes its internal map of available monster types. Specifically, it replaces all static references to EntityType enum values with a series of registration helper methods that try to resolve EntityType enum values from a given set of strings, stopping on the first match. If nothing matches, no registration, but a warning is logged unless a specific sentinel `null` value is passed as an argument, in which case the key is just silently skipped (not in use as of this commit, but it will be necessary for modern types like bees from 1.15+). While this is arguably a huge step back in terms of type safety, it does make the code base more resilient to API version bumps, and it allows compiling against modern API versions and still run on older (1.13-1.16) servers. It _does_ mean that changes to the EntityType enum (such as PIG_ZOMBIE to ZOMBIFIED_PIGLIN) must be discovered manually, which makes maintenance a little more difficult. The warning in the server log does make it fairly easy to fire up an early build of a new server version and check if everything initializes correctly.
MobArena 
MobArena is an arena-style minigame for Spigot-based Minecraft servers
Getting Started
If you don't want to compile the plugin yourself, grab a release artifact from one of these two sites:
The wiki here on Github should have all the information you need to get started using the plugin.
Getting Help
If you run into problems or need help with something, feel free to hop on the MobArena Discord server to have a chat: Instant Invite
Remember, though, that this communication channel is idle chat, which means you likely won't get a response immediately. It could take anything from a couple of seconds to a day, but your message will be seen.
Contributing
Found a bug, got a suggestion, or want to dig into the code base? There are many ways to contribute to the project!
Get started here: Contributing