@Override
    public PollResult poll(long currentTimeMs) {
        return pollInternal(
                prepareFetchRequests(),
                this::handleFetchSuccess,
                this::handleFetchFailure
        );
    }
@Test
    public void testMultipleAbortMarkers() {
        buildFetcher(OffsetResetStrategy.EARLIEST, new ByteArrayDeserializer(),
                new ByteArrayDeserializer(), Integer.MAX_VALUE, IsolationLevel.READ_COMMITTED);
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        int currentOffset = 0;

        currentOffset += appendTransactionalRecords(buffer, 1L, currentOffset,
                new SimpleRecord(time.milliseconds(), "abort1-1".getBytes(), "value".getBytes()),
                new SimpleRecord(time.milliseconds(), "abort1-2".getBytes(), "value".getBytes()));

        currentOffset += abortTransaction(buffer, 1L, currentOffset);
        // Duplicate abort -- should be ignored.
        currentOffset += abortTransaction(buffer, 1L, currentOffset);
        // Now commit a transaction.
        currentOffset += appendTransactionalRecords(buffer, 1L, currentOffset,
                new SimpleRecord(time.milliseconds(), "commit1-1".getBytes(), "value".getBytes()),
                new SimpleRecord(time.milliseconds(), "commit1-2".getBytes(), "value".getBytes()));
        commitTransaction(buffer, 1L, currentOffset);
        buffer.flip();

        List<FetchResponseData.AbortedTransaction> abortedTransactions = Collections.singletonList(
                new FetchResponseData.AbortedTransaction().setProducerId(1).setFirstOffset(0)
        );
        MemoryRecords records = MemoryRecords.readableRecords(buffer);
        assignFromUser(singleton(tp0));

        subscriptions.seek(tp0, 0);

        // normal fetch
        assertEquals(1, sendFetches());
        assertFalse(fetcher.hasCompletedFetches());

        client.prepareResponse(fullFetchResponseWithAbortedTransactions(records, abortedTransactions, Errors.NONE, 100L, 100L, 0));
        networkClientDelegate.poll(time.timer(0));
        assertTrue(fetcher.hasCompletedFetches());

        Map<TopicPartition, List<ConsumerRecord<byte[], byte[]>>> fetchedRecords = fetchRecords();
        assertTrue(fetchedRecords.containsKey(tp0));
        assertEquals(fetchedRecords.get(tp0).size(), 2);
        List<ConsumerRecord<byte[], byte[]>> fetchedConsumerRecords = fetchedRecords.get(tp0);
        Set<String> expectedCommittedKeys = new HashSet<>(Arrays.asList("commit1-1", "commit1-2"));
        Set<String> actuallyCommittedKeys = new HashSet<>();
        for (ConsumerRecord<byte[], byte[]> consumerRecord : fetchedConsumerRecords) {
            actuallyCommittedKeys.add(new String(consumerRecord.key(), StandardCharsets.UTF_8));
        }
        assertEquals(expectedCommittedKeys, actuallyCommittedKeys);
    }