docs: private String[] getServiceInterfaces(ServiceReference<ResourceFactory> ref) {
          Object createsObjectClass = ref.getProperty(ResourceFactory.CREATES_OBJECT_CLASS);
          if (createsObjectClass instanceof String[]) {
              Object createsObjectClassDefault = ref.getProperty("creates.objectClassDefault");
              if (createsObjectClassDefault instanceof String)
                  return new String[] { (String) createsObjectClassDefault };
              else if (createsObjectClassDefault instanceof String[])
                  return (String[]) createsObjectClassDefault;
              return (String[]) createsObjectClass;
          }
          if (createsObjectClass instanceof String) {
              return new String[] { (String) createsObjectClass };
          }
          return null;
      }