code: public static Object getPrivateAttribute(HttpServletRequest req, String key) {
          HttpServletRequest sr = getWrappedServletRequestObject(req);
          if (sr instanceof IPrivateRequestAttributes) {
              return ((IPrivateRequestAttributes) sr).getPrivateAttribute(key);
          } else {
              if (tc.isDebugEnabled()) {
                  Tr.debug(tc, "getPrivateAttribute called for non-IPrivateRequestAttributes object", req);
              }
              return null;
          }
      }
docs: Get private attribute value from the request (if applicable).
  If the request object is of an unexpected type, a {@code null} is returned.
  
  @param req
  @param key
  @return The attribute value, or {@code null} if the object type is unexpected
  @see IPrivateRequestAttributes#getPrivateAttribute(String)