public static boolean isNative(RunnerApi.PTransform pTransform) {
    // TODO(https://github.com/apache/beam/issues/20192) Use default (context) classloader.
    Iterator<IsNativeTransform> matchers =
        ServiceLoader.load(IsNativeTransform.class, NativeTransforms.class.getClassLoader())
            .iterator();
    while (matchers.hasNext()) {
      if (matchers.next().test(pTransform)) {
        return true;
      }
    }
    return false;
  }
@Test
  public void testNoMatch() {
    Assert.assertFalse(NativeTransforms.isNative(RunnerApi.PTransform.getDefaultInstance()));
  }