question: @ Override protected void onRewriteFailed ( final HttpServletRequest request , final HttpServletResponse response ) throws IOException { if ( log . isInfoEnabled ( ) ) log . info ( "Could not rewrite: request=" + request , new StackInfoReport ( ) ) ; final Boolean isLeaderRequest = isLeaderRequest ( request ) ; if ( isLeaderRequest == null ) { response . sendError ( HttpServletResponse . SC_INTERNAL_SERVER_ERROR , "Unknown prefix: requestURL=" + request . getRequestURL ( ) ) ; return ; } forwardToLocalService ( isLeaderRequest , request , response ) ; }
target:  Note: This offers an opportunity to handle a failure where we were unable to rewrite the request to some service, e.g., because the quorum is not met. The implementation is overridden to forward the request to the local service. The local service will then generate an appropriate HTTP error response.