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
} else {
                    
                }
            } catch (Exception e) {
                throw new RpcException(e);
            } finally {
                removeAttachment(ASYNC_KEY);
            }
        } catch (final RpcException e) {
            CompletableFuture<T> exceptionFuture = new CompletableFuture<>();
            exceptionFuture.completeExceptionally(e);
            return exceptionFuture;
        }
        return ((CompletableFuture<T>) getServiceContext().getFuture());
    }
    /**
     * one way async call, send request only, and result is not required
     *
     * @param runnable
     */
    @Override
    public void asyncCall(Runnable runnable) {
        try {
            setAttachment(RETURN_KEY, Boolean.FALSE.toString());
            runnable.run();
        } catch (Throwable e) {
            
            throw new RpcException("oneway call error ." + e.getMessage(), e);
        } finally {
            removeAttachment(RETURN_KEY);