docs: public void cacheValue(Object objKey, Object objValue)
      {
  //x        if ((objKey == null) || (objValue == null))
          if (objKey == null)
              return;
          Class<?> classKey = this.getField().getDataClass();
          objKey = this.convertKey(objKey, classKey);
          if (m_hmCache == null)
              m_hmCache = new HashMap<Object,Object>();
          m_hmCache.put(objKey, objValue);
      }