首先是dubbo的泛化广播调用，泛化调用方式为GSON
然后不是有个全链路追踪插件叫 sofa-tracer 嘛，sofa-tracer的dubbo filter拦截器工作时候，要从 RpcContext.getUrl()，但是发现get出来是个空导致空指针
![image](https://user-images.githubusercontent.com/42512469/195077820-0731c73e-bb4f-4088-9142-8e3abbde29c1.png)

但是我用常规自带的广播调用模式，就没问题，只有 broadcastCluster1Invoker 有问题
        <dependency>
            <groupId>org.apache.dubbo.extensions</groupId>
            <artifactId>dubbo-cluster-broadcast-1</artifactId>
            <version>1.0.0</version>
            <scope>provided</scope>
        </dependency>
就是上面这种，有问题
}
    @Override
    public RpcServiceContext setInvocation(Invocation invocation) {
        this.invocation = invocation;
        if (invocation != null) {
            setMethodName(invocation.getMethodName());
            setParameterTypes(invocation.getParameterTypes());
            setArguments(invocation.getArguments());
        }
        return this;
    }
    /**
     * Async invocation. Timeout will be handled even if <code>Future.get()</code> is not called.
     *
     * @param callable
     * @return get the return result from <code>future.get()</code>
     */
    @Override
    @SuppressWarnings("unchecked")
    public <T> CompletableFuture<T> asyncCall(Callable<T> callable) {
        try {
            try {
                setAttachment(ASYNC_KEY, Boolean.TRUE.toString());
                final T o = callable.call();
                
                if (o != null) {
                    if (o instanceof CompletableFuture) {
                        return (CompletableFuture<T>) o;
                    }
                    return CompletableFuture.completedFuture(o);