This test checks data nodes with an identifier have a type different then @Type="Unknown".
The default DataNode @Type is Unknown but if a data source is given, then there is a good
change it can be typed more specifically. For example, when the data source is Ensembl, then
the DataNode can be typed as GeneProduct. Similarly, when the data source is LIPID MAPS, then
the DataNode can be typed as Metabolite.
The solution is to open the pathway, find the DataNode with the given identifier, and change
the DataNode @Type to something different than Unknown.