code: private ProtoFile loadDescriptorProto() throws IOException {
      InputStream resourceAsStream = SchemaLoader.class.getResourceAsStream("/" + DESCRIPTOR_PROTO);
      try (BufferedSource buffer = Okio.buffer(Okio.source(resourceAsStream))) {
        String data = buffer.readUtf8();
        Location location = Location.get("", DESCRIPTOR_PROTO);
        ProtoFileElement element = ProtoParser.parse(location, data);
        return ProtoFile.get(element);
      }
    }
docs: Returns Google's protobuf descriptor, which defines standard options like default, deprecated,
  and java_package. If the user has provided their own version of the descriptor proto, that is
  preferred.