public static Map<String, FileWriteSchemaTransformFormatProvider> loadProviders() {
    return Providers.loadProviders(FileWriteSchemaTransformFormatProvider.class);
  }
@Test
  public void loadProviders() {
    Map<String, FileWriteSchemaTransformFormatProvider> formatProviderMap =
        FileWriteSchemaTransformFormatProviders.loadProviders();
    Set<String> keys = formatProviderMap.keySet();
    assertEquals(ImmutableSet.of(AVRO, CSV, JSON, PARQUET, XML), keys);
  }