This was deprecated with Bazel 0.8.0, which now uses
@com_google_protobuf instead.
This change will break users that use
grpc_java_repositories(omit_com_google_protobuf_java=True), so I've
added a custom error message to make the resolution clearer.
This commit aligns the naming of the Bazel Maven jars with the names
used by Bazel's migration-tooling project:
https://github.com/bazelbuild/migration-tooling
Unfortunately, we can't fix @com_google_protobuf_java because it's
required by Bazel itself.
Fixes#3328
Bazel third party dependencies are specified in repositories.bzl which
gives the consumer the ability to opt-out of any dependencies they use
directly in their own project.
Fixes#2756