How to log Protobuf string in nested objects in a human-readable way?

Question

Given a proto file:

syntax = "proto3";
package hello;

message TopGreeting {
    NestedGreeting greeting = 1;
}

message NestedGreeting {
    Greeting greeting = 1;
}

message Greeting {
    string message = 1;
}

and the code:

public class Main {
    public static void main(String[] args) {
        System.out.printf("From top: %s%n", newGreeting("오늘은 무슨 요일입니까?"));
        System.out.printf("Directly: %s%n", "오늘은 무슨 요일입니까?");
        System.out.printf("ByteString: %s", newGreeting("오늘은 무슨 요일입니까?").toByteString().toStringUtf8());
    }

    private static Hello.TopGreeting newGreeting(String message) {
        Hello.Greeting greeting = Hello.Greeting.newBuilder()
                .setMessage(message)
                .build();
        Hello.NestedGreeting nestedGreeting = Hello.NestedGreeting.newBuilder()
                .setGreeting(greeting)
                .build();
        return Hello.TopGreeting.newBuilder()
                .setGreeting(nestedGreeting)
                .build();
    }
}

Output

From top: greeting {
  greeting {
    message: "\354\230\244\353\212\230\354\235\200 \353\254\264\354\212\250 \354\232\224\354\235\274\354\236\205\353\213\210\352\271\214?"
  }
}

Directly: 오늘은 무슨 요일입니까?

ByteString: 
%
#
!오늘은 무슨 요일입니까?

How do I print the message in a human-readable way? As you can see, converting to ByteString prints the UTF-8 characters alright, but also prints some other garbage % and #.

Answer 1

Answering my own question, I solved this issue by digging through Protobuf source code.

System.out.println(TextFormat.printer().escapingNonAscii(false).printToString(greeting))

Output:

greeting {
  greeting {
    message: "오늘은 무슨 요일입니까?"
  }
}

toString uses the same mechanism but with escapingNonAscii(true) (default when omitted).

Also see this answer for how to convert Octal sequences to UTF-8 characters in case you don't have access to the source code, only logs.