final Object newException = request
.getAttribute("javax.servlet.error.exception");
// t==null means the attribute was not set.
if ((newException != null) && (newException == t)) {
request.removeAttribute("javax.servlet.error.exception");
}
// now clear the error code - to prevent double handling.
request.removeAttribute("javax.servlet.error.status_code");
request.removeAttribute("javax.servlet.error.request_uri");