private void consumeAbortedTransactionsUpTo(long offset) {
        if (abortedTransactions == null)
            return;

        while (!abortedTransactions.isEmpty() && abortedTransactions.peek().firstOffset() <= offset) {
            FetchResponseData.AbortedTransaction abortedTransaction = abortedTransactions.poll();
            abortedProducerIds.add(abortedTransaction.producerId());
        }
    }
Parse the record entry, deserializing the key / value fields if necessary
clients/src/main/java/org/apache/kafka/clients/consumer/internals/CompletedFetch.java