[Bug] About dubbo broadcast 2.6.X 2.7.X 3.X issue

[nuoqin]

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Apache Dubbo Component

Java SDK (apache/dubbo)

Dubbo Version

2.7.X 3.X

Steps to reproduce this issue

When our system is upgraded from alibaba dubbo 2.6.X to 2.7.X/3.X, when we use ReferenceConfig and find registryConfig.setCluster(ClusterRules.BROADCAST), we find that broadcast is supported in version 2.6.X
to services on other servers. However, when upgrading to 2.7.X/3.X, the service cannot broadcast.

2.6.X code is as follows

ReferenceConfig<CacheService> reference = new ReferenceConfig<>();
RegistryConfig registryConfig = new RegistryConfig("zookeeper地址");
**registryConfig.setCluster(ClusterRules.BROADCAST);**
reference.setRegistry(registryConfig); 
//设置ApplicationConfig
reference.setApplication(application);
reference.setInterface(CacheSyncService.class);

CacheService service = reference.get();

service.update();

2.7.X/3.X code is as follows

ReferenceConfig<CacheService> reference = new ReferenceConfig<>();
RegistryConfig registryConfig = new RegistryConfig("zookeeper地址");
reference.setRegistry(registryConfig); 
//设置ApplicationConfig
reference.setApplication(application);
reference.setInterface(CacheSyncService.class);
**reference.setCluster(ClusterRules.BROADCAST);**

CacheService service = reference.get();

service.update();

But in the official documentation, there is no hint,I wonder if users should be informed of this change，Thanks

What you expected to happen

A version upgrade makes the service unavailable

Anything else

No response

Are you willing to submit a pull request to fix on your own?

• Yes I am willing to submit a pull request on my own!

Code of Conduct

• I agree to follow this project's Code of Conduct

[nuoqin]

Close the issue and resubmit it to the address below. I'm sorry
https://github.com/apache/dubbo/issues/14280