USDA has a WFS service to get soil type polygons for an area. However, when using your wfsFeatureLayer to get the available columns, the ObjectID column is listed twice. Using the native http request, one can see that this column is indeed returned twice by the service. I assume this is an error on their part, and we have notified them of this issue. However, as expected... no response.
When we call the GetFeaturesInBoundingBox function on your wfsFeatureLayer, you throw an internal exception because of the duplicate column name... even when we ask to have no columns returned.
Could you consider an enhancement to the wfsFeatureLayer to be more forgiving of misbehaving WFS sources? Trap for duplicate columns, etc?
The service is: sdmdataaccess.nrcs.usda.gov/Spatial/SDMWGS84Geographic.wfs
Thanks!