@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    if (((bitField0_ & 0x00000001) != 0)) {
      output.writeMessage(1, getModule());
    }
    if (((bitField0_ & 0x00000002) != 0)) {
      output.writeMessage(2, getBuildId());
    }
    getUnknownFields().writeTo(output);
  }
<pre>
A unique identifier for the module, usually a hash of its
contents (up to 128 bytes).
</pre>

<code>.google.devtools.cloudtrace.v2.TruncatableString build_id = 2;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Module.java