message: Fix bug in _add_item_to_params when setting tf.HParams.
diff: @@ -3143,7 +3143,7 @@ def _add_item_to_params(params, key, value):
  if isinstance(params, hparam.HParams):
  # For HParams, we need to use special API.
  if key in params:
  - params.key = value
  + params.set_hparam(key, value)
  else:
  params.add_hparam(key, value)
  else:
  