private String getUniqueId(ProviderConfig providerConfig) {
        String uniqueId = providerConfig.getUniqueId();
        return null == uniqueId ? "" : uniqueId;
    }
get unique id from provider config, this function won't return null

@param providerConfig provider config
@return unique id in provider config
remoting/remoting-triple/src/main/java/com/alipay/sofa/rpc/server/triple/UniqueIdInvoker.java