code: public static String syncRestCall(final String purl) {
      try {
        return CACHE.get(purl);
      } catch (final ExecutionException e) {
        GWT.log(e.getMessage(), e);
        return null;
      }
    }
docs: start get rest call with given url.
  
  @param purl url to read
  @return result of the call, has to be interpreted