This project contains two "projects". A client and a server. The server publishes a pure protobuf jar. No dependencies. I can't figure out how to trick the other server projects to depend on it directly, so I went the cheeky route and symlinked them into the protocol subproject. The client depends on the "published" protobuf jar. You can test this with publishLocal to get it into your local ivy. The client depends on this jar with a protobuf configuration. This pulls it into the protobuf_external folder by default. We'd like to get the generated code from it, so we include the parent folder then filter out other things in that folder. Why? So we can use the same structure in our includes as in the jar.
Different code gen settings even across scalapb mean that if you say lump the protos into a folder, publish code into it and then publish that you are pinning you .protos to a given scala binary version, and forcing downstream dependencies to use identical code gen (think flatPackage and frields) if they do any includes. It also makes the jar totally annoying for other jvm users.