Trying to follow (without downloading code) https://subscription.packtpub.com/book/web_development/9781839211744/1
In my local machine, this generator command did works
protoc --go_out=. --go-grpc_out=. ./proto/sfapi.proto
Refs: golang/protobuf#1070 (comment)
Refs: https://stackoverflow.com/a/69302744
After service code generation, we need to adjust this private method implementation, mustEmbedUnimplementedStarfriendsServer().