private Map<Uuid, String> topicNames(List<TopicIdPartition> partitions) {
        Map<Uuid, String> topicNames = new HashMap<>();
        partitions.forEach(partition -> topicNames.putIfAbsent(partition.topicId(), partition.topic()));
        return topicNames;
    }
This validates that no records are fetched for partitions that are waiting for the
onPartitionsAssigned callback to complete. Note that this markPendingOnAssignedCallback
functionality is only used from the {@link AsyncKafkaConsumer}.
clients/src/test/java/org/apache/kafka/clients/consumer/internals/FetchRequestManagerTest.java