docs: private List<CmsProperty> compareProperties(
          CmsObject cms,
          CmsResourceImportData resData,
          CmsResource existingResource)
      throws CmsException {
  
          if (existingResource == null) {
              return Collections.emptyList();
          }
  
          Map<String, CmsProperty> importProps = resData.getProperties();
          Map<String, CmsProperty> existingProps = CmsProperty.getPropertyMap(
              cms.readPropertyObjects(existingResource, false));
          Map<String, CmsProperty> propsToWrite = new HashMap<>();
          Set<String> keys = new HashSet<>();
          keys.addAll(existingProps.keySet());
          keys.addAll(importProps.keySet());
  
          for (String key : keys) {
              CmsProperty existingProp = existingProps.get(key);
              CmsProperty importProp = importProps.get(key);
              if (existingProp == null) {
                  propsToWrite.put(key, importProp);
              } else if (importProp == null) {
                  propsToWrite.put(key, new CmsProperty(key, "", ""));
              } else if (!existingProp.isIdentical(importProp)) {
                  propsToWrite.put(key, importProp);
              }
          }
          return new ArrayList<>(propsToWrite.values());
  
      }