@Override
    public boolean isCircuitTrippingException(Throwable e) {
        if (e instanceof UnexpectedHttpResponseException) {
            return ((UnexpectedHttpResponseException) e).getStatusCode() == 503;
        } else if (e instanceof ClientException) {
            return ((ClientException) e).getErrorType() == ClientException.ErrorType.SERVER_THROTTLED;
        }
        return super.isCircuitTrippingException(e);
    }
@return true if the Throwable has one of the following exception type as a cause: 
{@link SocketException}, {@link SocketTimeoutException}
ribbon-transport/src/main/java/com/netflix/ribbon/transport/netty/http/NettyHttpLoadBalancerErrorHandler.java