<@U2E974ELT> gRPC already generates async java st...

# coroutines

[ehubbard]

@elizarov gRPC already generates async java stubs. So it feels like we should be able to write an adapter or something. This would let folks utilize all of the google cloud service APIs, or anything else authored with the gRPC protocol. Not sure if they are doing Completable Futures, a uniform Callback, or auto-generated custom callback definitions for each and every RPC call. Maybe I’ll take a gander at it…