default Set<GroupProtocol> supportedGroupProtocols() {
        Map<String, String> serverProperties = config().serverProperties();
        Set<GroupProtocol> supportedGroupProtocols = new HashSet<>();
        supportedGroupProtocols.add(CLASSIC);

        if (serverProperties.getOrDefault(GROUP_COORDINATOR_REBALANCE_PROTOCOLS_CONFIG, "").contains("consumer")) {
            supportedGroupProtocols.add(CONSUMER);
        }

        return Collections.unmodifiableSet(supportedGroupProtocols);
    }
The underlying object which is responsible for setting up and tearing down the cluster.
core/src/test/java/kafka/test/ClusterInstance.java