anchor.diff:  %%--------------------------------------------------------------------
   -spec prepare_user_ctx_params(name(), ctx()) -> ctx().
   prepare_user_ctx_params(HelperName = ?WEBDAV_HELPER_NAME, Params) ->
  -    Transformed = maps_flatmap(fun
  +    Ctx = maps_flatmap(fun
           (Key = <<"onedataAccessToken">>, Token) when byte_size(Token) > 0 ->
               {ok, AdminId} = user_identity:get_or_fetch_user_id(Token),
               #{
  
positive.code:             };
          (Key, Value) -> #{Key => Value}
      end, Params),
      filter_fields(expected_user_ctx_params(HelperName), Transformed);
  
  prepare_user_ctx_params(HelperName, Params) ->
      filter_fields(expected_user_ctx_params(HelperName), Params).
  
negative.code:     end, Fields).
  
  
  %% @private
  -spec remove_field(ToRemove :: field(), Fields :: [field() | optional_field()]) ->
      [field() | optional_field()].
  remove_field(ToRemove, Fields) ->
      lists:filter(fun(Field) -> case Field of
          ToRemove -> false;
          {optional, ToRemove} -> false;
          _ -> true
      end end, Fields).
  
  
  %%--------------------------------------------------------------------
  %% @private
  %% @doc
  