public static Set<String> fetchBrokerNameByClusterName(final MQAdminExt adminExt, final String clusterName)
        throws Exception {
        ClusterInfo clusterInfoSerializeWrapper = adminExt.examineBrokerClusterInfo();
        Set<String> brokerNameSet = clusterInfoSerializeWrapper.getClusterAddrTable().get(clusterName);
        if (brokerNameSet == null || brokerNameSet.isEmpty()) {
            throw new Exception(ERROR_MESSAGE);
        }
        return brokerNameSet;
    }
@Test
    public void testFetchBrokerNameByClusterName() throws Exception {
        Set<String> result = CommandUtil.fetchBrokerNameByClusterName(defaultMQAdminExtImpl, "default-cluster");
        assertThat(result.contains("default-broker")).isTrue();
        assertThat(result.contains("default-broker-one")).isTrue();
        assertThat(result.size()).isEqualTo(2);
    }