public SortedSet<TopicPartition> partitions() {
        return partitions;
    }
Event that signifies that the network I/O thread wants to invoke one of the callback methods on the
{@link ConsumerRebalanceListener}. This event will be processed by the application thread when the next
{@link Consumer#poll(Duration)} call is performed by the user. When processed, the application thread should
invoke the appropriate callback method (based on {@link #methodName()}) with the given partitions.
clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/ConsumerRebalanceListenerCallbackNeededEvent.java