docs: public List<String> differentValues(CdoSnapshotState previous) {
          List<String> different = new ArrayList<>();
  
          for (String propertyName : properties.keySet()) {
              if (previous.isNull(propertyName)){
                  continue;
              }
              if (!propertyEquals(previous, propertyName)){
                  different.add(propertyName);
              }
          }
  
          //add nullified
          different.addAll(Sets.xor(properties.keySet(), previous.properties.keySet()));
  
          return different;
      }