See com.google.protobuf.CodedInputStream#readMessage.
See com.google.protobuf.CodedInputStream#readMessage.
CodedInputStream#readMessage attempts to mutate the passed Builder and discards the returned value, which we need, since our "Builders" (Messages) return a new instance whenever a mutation is performed.
Message trait for extendable messages generated with ScalaBuff. Ordinarily Messages would have GeneratedMessageLite.Builder mixed in, but since it's a Java class, we can't do that. Contains methods implementing the MessageLite.Builder Java interface, similar to ones in GeneratedMessageLite.Builder.