docs: public ImageIcon getCacheValue(Object objKey)
      {
          if (m_hmCache == null)
              return null;
          if (objKey == null)
              return null;
          Class<?> classKey = this.getField().getDataClass();
          objKey = this.convertKey(objKey, classKey);
          return (ImageIcon)m_hmCache.get(objKey);
      }