@Test
    public void testDescribeMultipleConsumerGroups() {
        try (AdminClientUnitTestEnv env = new AdminClientUnitTestEnv(mockCluster(1, 0))) {
            env.kafkaClient().setNodeApiVersions(NodeApiVersions.create());

            env.kafkaClient().prepareResponse(prepareFindCoordinatorResponse(Errors.NONE, env.cluster().controller()));

            // The first request sent will be a ConsumerGroupDescribe request. Let's
            // fail it in order to fail back to using the classic version.
            env.kafkaClient().prepareUnsupportedVersionResponse(
                request -> request instanceof ConsumerGroupDescribeRequest);

            TopicPartition myTopicPartition0 = new TopicPartition("my_topic", 0);
            TopicPartition myTopicPartition1 = new TopicPartition("my_topic", 1);
            TopicPartition myTopicPartition2 = new TopicPartition("my_topic", 2);

            final List<TopicPartition> topicPartitions = new ArrayList<>();
            topicPartitions.add(0, myTopicPartition0);
            topicPartitions.add(1, myTopicPartition1);
            topicPartitions.add(2, myTopicPartition2);

            final ByteBuffer memberAssignment = ConsumerProtocol.serializeAssignment(new ConsumerPartitionAssignor.Assignment(topicPartitions));
            byte[] memberAssignmentBytes = new byte[memberAssignment.remaining()];
            memberAssignment.get(memberAssignmentBytes);

            DescribeGroupsResponseData group0Data = new DescribeGroupsResponseData();
            group0Data.groups().add(DescribeGroupsResponse.groupMetadata(
                    GROUP_ID,
                    Errors.NONE,
                    "",
                    ConsumerProtocol.PROTOCOL_TYPE,
                    "",
                    asList(
                            DescribeGroupsResponse.groupMember("0", null, "clientId0", "clientHost", memberAssignmentBytes, null),
                            DescribeGroupsResponse.groupMember("1", null, "clientId1", "clientHost", memberAssignmentBytes, null)
                    ),
                    Collections.emptySet()));

            DescribeGroupsResponseData groupConnectData = new DescribeGroupsResponseData();
            group0Data.groups().add(DescribeGroupsResponse.groupMetadata(
                    "group-connect-0",
                    Errors.NONE,
                    "",
                    "connect",
                    "",
                    asList(
                            DescribeGroupsResponse.groupMember("0", null, "clientId0", "clientHost", memberAssignmentBytes, null),
                            DescribeGroupsResponse.groupMember("1", null, "clientId1", "clientHost", memberAssignmentBytes, null)
                    ),
                    Collections.emptySet()));

            env.kafkaClient().prepareResponse(new DescribeGroupsResponse(group0Data));
            env.kafkaClient().prepareResponse(new DescribeGroupsResponse(groupConnectData));

            Collection<String> groups = new HashSet<>();
            groups.add(GROUP_ID);
            groups.add("group-connect-0");
            final DescribeConsumerGroupsResult result = env.adminClient().describeConsumerGroups(groups);
            assertEquals(2, result.describedGroups().size());
            assertEquals(groups, result.describedGroups().keySet());
        }
    }
Test that we propagate exceptions encountered when fetching metadata.
clients/src/test/java/org/apache/kafka/clients/admin/KafkaAdminClientTest.java