Methods are now properly annotated @Nullable when they may return null. More descriptive exceptions are thrown when issues occur instead of just returning null.
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.
This is much more user-friendly - users can either compile a specific module or create a profile to compile for the specific Minecraft versions they're looking to support. It means that it's much easier for people to continue assisting with the development of OpenInv in the future without access to every version of CB since 1.4.5.
This commit restores and updates most of the old system.
