public boolean equivalentWasDerivedFroms (WasDerivedFrom description1, WasDerivedFrom description2) {
        return bothNull (description1, description2)
               || (neitherNull (description1, description2)
                   && equivalentIdentifiers (description1, description2)
                   && equivalentAttributes (description1, description2)
                   && equivalentEntities (description1.getDerived (), description2.getDerived ())
                   && equivalentEntities (description1.getDerivedFrom (), description2.getDerivedFrom ())
                   && equivalentActivities (description1.getDeriver (), description2.getDeriver ())
                   && equivalentWasGeneratedBys (description1.getGeneration (), description2.getGeneration ())
                   && equivalentUseds (description1.getUsage (), description2.getUsage ()));
    }