- [ ] I have searched the [issues](https://github.com/apache/incubator-dubbo/issues) of this repository and believe that this is not a duplicate.
- [ ] I have checked the [FAQ](https://github.com/apache/incubator-dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: xxx
* Operating System version: xxx
* Java version: xxx

### Steps to reproduce this issue

1. xxx
2. xxx
3. xxx

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

private <T> ExporterChangeableWrapper doChangeLocalExport(final Invoker<T> originInvoker, URL newInvokerUrl) {
        String key = getCacheKey(originInvoker);
        final ExporterChangeableWrapper<T> exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
        if (exporter == null) {
            logger.warn(new IllegalStateException("error state, exporter should not be null"));
        } else {
            final Invoker<T> invokerDelegate = new InvokerDelegate<T>(originInvoker, newInvokerUrl);
            exporter.setExporter(protocol.export(invokerDelegate));
        }
        return exporter;
    }
    /**
     * Get an instance of registry based on the address of invoker
     *
     * @param originInvoker
     * @return
     */
    private Registry getRegistry(final Invoker<?> originInvoker) {
        URL registryUrl = getRegistryUrl(originInvoker);
        return registryFactory.getRegistry(registryUrl);
    }
    private URL getRegistryUrl(Invoker<?> originInvoker) {
        URL registryUrl = originInvoker.getUrl();
        if (REGISTRY_PROTOCOL.equals(registryUrl.getProtocol())) {
            String protocol = registryUrl.getParameter(REGISTRY_KEY, DEFAULT_DIRECTORY);
            registryUrl = registryUrl.setProtocol(protocol).removeParameter(REGISTRY_KEY);
        }
        return registryUrl;
    }
    /**