docs: synchronized void sendInitialMessage(Node node) {
      io.opencensus.proto.trace.v1.TraceConfig currentTraceConfigProto =
          TraceProtoUtils.getCurrentTraceConfig(traceConfig);
      // First config must have Node set.
      CurrentLibraryConfig firstConfig =
          CurrentLibraryConfig.newBuilder().setNode(node).setConfig(currentTraceConfigProto).build();
      sendCurrentConfig(firstConfig);
    }