C'mon Spigot team, this is why the revision bumps existed in the first place, to allow plugins that deal with NMS to easily and gracefully fail on unsupported versions. 1.11.1 should be R2, 1.11.2 should be R3. I get that NMS isn't officially supported, but honestly, either do away with the versioned packages entirely or keep up with them properly. It's a single string change, it's not like it's prohibitively difficult.
The project was very messy and due to older Bukkit packaging conventions, 1_4_5 and 1_4_6 were sorted away from the rest of the versioned code. All of the versioned internals are now submodules of the internal module.
Rather than use the hackish existing method of abusing the shade plugin to combine "dependencies" for a dummy assembly project, we're actually using the assembly plugin.
Profiles are still split up between the parent pom and the internal module pom, but they're much more clean.
The API is now its own module and can be compiled and released as a separate file for developers. Soon, Bukkit ticket 20, you'll be closed.