text: syntax = "proto3";
  
  option java_package = "com.example.tutorial";
  option java_outer_classname = "OuterSample";
  option java_multiple_files = true;
  
  // From the main sourceSet
  import "helloworld.proto";
  
  message Msg {
      string foo = 1;
      SecondMsg blah = 2;
  }
  
  message SecondMsg {
      int32 blah = 1;
      helloworld.HelloReply reply = 2;
  }
  