docs: String getFilterQuery() {
  
          String result = m_config.getFilterQuery();
          if (result == null) {
              result = "";
          }
          if (CmsStringUtil.isNotEmptyOrWhitespaceOnly(result) && !result.startsWith("&")) {
              result = "&" + result;
          }
          if (!result.contains(CommonParams.FL + "=")) {
              result += "&" + CommonParams.FL + "=" + getDefaultReturnFields();
          }
          I_CmsListDateRestriction dateRestriction = m_config.getDateRestriction();
          if (dateRestriction != null) {
              result += "&fq="
                  + CmsSearchField.FIELD_INSTANCEDATE_CURRENT_TILL
                  + "_"
                  + getSearchLocale().toString()
                  + "_dt:"
                  + dateRestriction.getRange();
  
          }
          return result;
      }