Writing nested attributes from a GML to a PostGis table

I have several GML files that I read via the FeatureReader, and format =«GML» and reading all feature types. An unknown amount of these GML files results in Nested Attributes. Nested Attributes is appearing in the workflow as lists with one to several sub-levels. So far so good. But the problem occurs when I want to use the jsonpacker to create json strings that I am able to write to a PostGis table. The jsonpacker demands that I declare what attribute to pack. But making a generic workflow to handle any GML files and then pack all the lists without knowing the names of the lists at forehand, makes this a difficult task. I need one json string for every list, and the name of the json attribute should be the top level name in every list. So in stort : I am creating a generic workspace that packs all lists individually to just as many unique json string attributes. Sorry for not posting any pictures of the workspace, but all I have is a generic reader of GML files that results in an unknown amount of nested attributes.