code: public static void removePrivateAttribute(HttpServletRequest req, String key) {
          HttpServletRequest sr = getWrappedServletRequestObject(req);
          if (sr instanceof IPrivateRequestAttributes) {
              ((IPrivateRequestAttributes) sr).removePrivateAttribute(key);
          } else {
              if (tc.isDebugEnabled()) {
                  Tr.debug(tc, "getPrivateAttribute called for non-IPrivateRequestAttributes object", req);
              }
          }
      }
docs: Remove a private attribute from the request (if applicable).
  If the request object is of an unexpected type, no operation occurs.
  
  @param req
  @param key
  @see IPrivateRequestAttributes#removePrivateAttribute(String)