@VisibleForTesting
  @Nullable
  Integer getUploadBufferSizeBytes() {
    return uploadBufferSizeBytes;
  }
@Test
  public void testUploadBufferSizeDefault() {
    GcsOptions pipelineOptions = gcsOptionsWithTestCredential();
    GcsUtil util = pipelineOptions.getGcsUtil();
    assertNull(util.getUploadBufferSizeBytes());
  }