message: raise proper exception when a dir path is passed to ParquetIODataset
diff: @@ -27,6 +27,11 @@ class ParquetIODataset(tf.data.Dataset):
  """ParquetIODataset."""
  assert internal
  with tf.name_scope("ParquetIODataset"):
  + if tf.io.gfile.isdir(filename):
  + raise ValueError(
  + "passing a directory path to 'filename' is not supported. "
  + "Use 'tf.data.Dataset.list_files()' with a map() operation instead."
  + )
  components, shapes, dtypes = core_ops.io_parquet_readable_info(
  filename, shared=filename, container="ParquetIODataset"
  )
  