message: Reduce the usage of keras generic util for Feature column.
diff: @@ -84,8 +84,7 @@ def serialize_feature_column(fc):
  if isinstance(fc, six.string_types):
  return fc
  elif isinstance(fc, fc_lib.FeatureColumn):
  - return generic_utils.serialize_keras_class_and_config(
  - fc.__class__.__name__, fc.get_config()) # pylint: disable=protected-access
  + return {'class_name': fc.__class__.__name__, 'config': fc.get_config()}
  else:
  raise ValueError('Instance: {} is not a FeatureColumn'.format(fc))
  