I mean, I make FoxGuard, which is aimed as being a WorldGuard replacement built on SpongeAPI.
So I doubt anything is super secret…
On the plus side, if you post source code, you protect yourself from people who can AND WILL decompile, copy, and paste code and call it their own.
Making it open source prevents that, as you can very clearly prove that you own the code.
It’s also the reason that if you look at my code, I have copyright info on the top of every file.
It’s okay if you don’t particularly want to share code, i’m just saying that it’s better. ^^