private String computeSearchKey(
     String prefix, IMarket market, ICategory category, String queryText) {
   return prefix
       + ":"
       + (market == null ? "" : market.getId())
       + ":"
       + (category == null ? "" : category.getId())
       + ":"
       + (queryText == null
           ? ""
           : queryText
               .trim()); //$NON-NLS-1$ //$NON-NLS-2$//$NON-NLS-3$//$NON-NLS-4$//$NON-NLS-5$
                         // //$NON-NLS-6$
 }
 private String computeCategoryKey(ICategory category) {
   if (category.getId() != null) {
     return "Category:" + category.getId(); // $NON-NLS-1$
   }
   return null;
 }