Fix: Fix getGmlObject() in GenericCityObject

CityDoctorParent/CityDoctorModel/src/main/java/de/hft/stuttgart/citydoctor2/datastructure/GenericCityObject.java

@@ -198,7 +198,7 @@ public class GenericCityObject extends CityObject {
 
     @Override
     public AbstractCityObject getGmlObject() {
-        return null;
+        return cgmlGos;
     }
 
     @Override