see more from https://github.com/openzipkin/brave/issues/867, also see https://github.com/apache/incubator-dubbo/issues/3576
}
    /**
     * remove context.
     *
     * @see org.apache.dubbo.rpc.filter.ContextFilter
     */
    public static void removeContext() {
        LOCAL.remove();
    }
    /**
     * Get the request object of the underlying RPC protocol, e.g. HttpServletRequest
     *
     * @return null if the underlying protocol doesn't provide support for getting request
     */
    public Object getRequest() {
        return request;
    }
    public void setRequest(Object request) {
        this.request = request;
    }
    /**
     * Get the request object of the underlying RPC protocol, e.g. HttpServletRequest
     *
     * @return null if the underlying protocol doesn't provide support for getting request or the request is not of the specified type
     */
    @SuppressWarnings("unchecked")
    public <T> T getRequest(Class<T> clazz) {
        return (request != null && clazz.isAssignableFrom(request.getClass())) ? (T) request : null;
    }
    /**