code: @GwtIncompatible("Unnecessary")
    private void outputModuleGraphJson() throws IOException {
      if (config.outputModuleDependencies != null &&
          config.outputModuleDependencies.length() != 0) {
        try (Writer out = fileNameToOutputWriter2(config.outputModuleDependencies)) {
          printModuleGraphJsonTo(out);
        }
      }
    }
docs: Creates a file containing the current module graph in JSON serialization.