default List<RebalanceProtocol> supportedProtocols() {
        return Collections.singletonList(RebalanceProtocol.EAGER);
    }
Indicate which rebalance protocol this assignor works with;
By default it should always work with {@link RebalanceProtocol#EAGER}.
clients/src/main/java/org/apache/kafka/clients/consumer/ConsumerPartitionAssignor.java