WFS 2.0 cascaded stored query

Support for cascaded stored query backed layers from wfs-ng datastores.
This may be a question for Andrea:

I am not sure about this API change, we may need to add a method for compatibility:

GeoServerFeatureSource(source, schema, definitionQuery, declaredCRS, srsHandling, linearizationTolerance){
   this( source, schema, definitionQuery, declaredCRS, srsHandling, linearizationTolerance, null );
}

Or is it the intention force compile errors and ask all code to supply a metadata map?

I would also consider using a parameter object as we have a possible open ended set of parameters that can be supplied to this class over time (as it takes on more responsibilities as a bridge).  Example: we may wish a hint to force feature id (as we do with feature creation).