public Map<TopicPartition, String> partitionsTransferringOwnership() {
        return partitionsTransferringOwnership;
    }
Returns true iff all consumers have an identical subscription. Also fills out the passed in
{@code consumerToOwnedPartitions} with each consumer's previously owned and still-subscribed partitions,
and the {@code partitionsWithMultiplePreviousOwners} with any partitions claimed by multiple previous owners
clients/src/main/java/org/apache/kafka/clients/consumer/internals/AbstractStickyAssignor.java