docs: private void deleteFromIndices(ApiType oldObj, String key) {
      for (Map.Entry<String, Function<ApiType, List<String>>> indexEntry : this.indexers.entrySet()) {
        Function<ApiType, List<String>> indexFunc = indexEntry.getValue();
        List<String> indexValues = indexFunc.apply(oldObj);
        if (io.kubernetes.client.util.common.Collections.isEmptyCollection(indexValues)) {
          continue;
        }
  
        Map<String, Set<String>> index = this.indices.get(indexEntry.getKey());
        if (index == null) {
          continue;
        }
        for (String indexValue : indexValues) {
          Set<String> indexSet = index.get(indexValue);
          if (indexSet != null) {
            indexSet.remove(key);
          }
        }
      }
    }