Contributing is easy, there are only a few things you should follow.
It is of my understanding that my formatting standards are not Java conventions, so I'll list the generalized rules below:
finals: SCREAMING_SNAKE_CASE
public: PascalCase
private/package-private/protected: camelCase
packages: lowercase
When contributing an interface, it should be under the following package: tomat.dev.bridge.full.original.package.IOriginalClassNameBridge
For example, dev.tomat.mojang.NameHistoryEntry becomes tomat.dev.bridge.dev.tomat.mojang.INameHistoryEntryBridge.
Of course, having dev.tomat in there twice looks ugly, but other packages look better, I swear.