String validateQuery(String queryInUrl, String queryInBody) {

    if (!(StringUtils.hasText(queryInUrl) || StringUtils.hasText(queryInBody))) {
      throw new GemfireRestException("could not process null value specified in query String");
    }
    return (StringUtils.hasText(queryInUrl) ? decode(queryInUrl) : queryInBody);
  }
AbstractBaseController class contains common functionalities required for other controllers.

@since GemFire 8.0
geode-web-api/src/main/java/org/apache/geode/rest/internal/web/controllers/AbstractBaseController.java