docs: protected static boolean match(Object ref, Object test) {
      if(ref == null) {
        return false;
      }
      // Cheap and fast, may hold for class labels!
      if(ref == test) {
        return true;
      }
      if(ref instanceof LabelList && test instanceof LabelList) {
        final LabelList lref = (LabelList) ref;
        final LabelList ltest = (LabelList) test;
        final int s1 = lref.size(), s2 = ltest.size();
        if(s1 == 0 || s2 == 0) {
          return false;
        }
        for(int i = 0; i < s1; i++) {
          String l1 = lref.get(i);
          if(l1 == null) {
            continue;
          }
          for(int j = 0; j < s2; j++) {
            if(l1.equals(ltest.get(j))) {
              return true;
            }
          }
        }
      }
      // Fallback to equality, e.g. on class labels
      return ref.equals(test);
    }