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
*
     * @return remote address string.
     */
    @Override
    public String getRemoteAddressString() {
        return getRemoteHost() + ":" + getRemotePort();
    }
    /**
     * get remote host name.
     *
     * @return remote host name
     */
    @Override
    public String getRemoteHostName() {
        return remoteAddress == null ? null : remoteAddress.getHostName();
    }
    /**
     * get local host.
     *
     * @return local host
     */
    @Override
    public String getLocalHost() {
        String host = localAddress == null ? null :
                localAddress.getAddress() == null ? localAddress.getHostName()
                        : NetUtils.filterLocalHost(localAddress.getAddress().getHostAddress());
        if (host == null || host.length() == 0) {
            return NetUtils.getLocalHost();
        }
        return host;