@java.lang.Override
  protected Builder newBuilderForType(com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
    Builder builder = new Builder(parent);
    return builder;
  }
<pre>
Required. ID of the trace to return.
</pre>

<code>string trace_id = 2 [(.google.api.field_behavior) = REQUIRED];</code>

@return The bytes for traceId.
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/GetTraceRequest.java