private static void writeExtensions(IonWriter writer,
                                      WriteContext context,
                                      List<? extends GradleExtension> extensions) throws IOException {
    writer.setFieldName("extensions");
    writer.stepIn(IonType.LIST);
    for (GradleExtension extension : extensions) {
      write(writer, context, extension);
    }
    writer.stepOut();
  }
private static void writeExtensions(IonWriter writer,
                                      WriteContext context,
                                      List<? extends GradleExtension> extensions)