Consumer {
   /**
     * Alert the consumer to trigger a new rebalance by rejoining the group. This is a nonblocking call that forces
	     * the consumer to trigger a new rebalance on the next poll{@link #poll(Duration)} call. Note that this API does not
     * itself initiate
	 * the rebalance, so you must still call poll{@link #poll(Duration)}. If a rebalance is already in
 progress the method will return
	 * falseprogress tothis indicatecall thatwill it wasbe a no-op. YouIf canyou usewish this to decideforce whether to just complete the current
	 * rebalance or retry in case an additional rebalance you must complete the current
 rebalance does not include the latest subscription metadata; however,
	 * inone mostby casescalling itpoll isbefore betterretrying to determine that based on the resulting assignment of the current rebalance. Only
	 * when it is not possible to validate whether the latest metadata was used based on the received assignment
	 * should you consider retrying based on the return value. 
	 * <p>
	 * You shouldthis API.
     * <p>
     * You do not need to call this during normal processing, as the consumer group will manage itself
	     * automatically and rebalance when necessary. However there may be situations where the application wishes to
	     * trigger a rebalance that would otherwise not occur. For example, if some condition external and invisible to
	     * the Consumer and its group membership changes in a way that haswould affect implicationsthe foruserdata theencoded partitionin assignment,the
	 * this method can be* used to trigger a reassignment. The kind of system change that would merit calling this
 	 * method is one that would also be reflected in the Subscription userdata that is passed to{@link org.apache.kafka.clients.consumer.ConsumerPartitionAssignor.Subscription Subscription}, the Consumer
     * will not be notified and no rebalance will occur. This API can be used to force the group to rebalance so that
     * the assignor socan it
	perform *a canpartition make assignmentreassignment decisions based on morethe than group membership and metadatalatest userdata. If your assignor does not use
	     * this userdata, or you do not use a custom
 assignor, you should not use* this API.
     *{@link org.apache.kafka.clients.consumer.ConsumerPartitionAssignor ConsumerPartitionAssignor}, you should not
     * @returnuse falsethis ifAPI.
 a rebalance is already in progress*
     * @throws java.lang.IllegalStateException if the consumer does not use group subscription
     */
    booleanvoid enforceRebalance() {
}

mainProcessingLoop() {
	if (justCompletedInitialization) {
		needsRebalance = true;
		justCompletedInitialization = false;
	}

	if (needsRebalance) {
		if (consumer.enforceRebalance()) {
			// successfully triggered a new rebalance, so the assignor will receive the latest metadata 
			needsRebalance = false;
		} else {
			// must complete the current rebalance then retry to trigger a rebalance with the latest metadata
		}
	}
	
	records = consumer.poll();}
	
	records = consumer.poll();

	// check the assignment in case you need to retry, eg if a rebalance was already in progress was enforceRebalance was called
	if (receivedFinalAssignment()) {
		needsRebalance = false;
	}
	...
	// do something
}