private void maybeScheduleNextExpiredDelegationTokenSweep() {
        if (featureControl.metadataVersion().isDelegationTokenSupported() &&
            delegationTokenControlManager.isEnabled()) {

            log.debug(
                "Scheduling write event for {} because DelegationTokens are enabled.",
                SWEEP_EXPIRED_DELEGATION_TOKENS
            );

            ControllerWriteEvent<Void> event = new ControllerWriteEvent<>(
                SWEEP_EXPIRED_DELEGATION_TOKENS,
                () -> {
                    maybeScheduleNextExpiredDelegationTokenSweep();

                    return ControllerResult.of(
                        delegationTokenControlManager.sweepExpiredDelegationTokens(), null);
                },
                EnumSet.of(DOES_NOT_UPDATE_QUEUE_TIME)
            );

            long delayNs = time.nanoseconds() +
                NANOSECONDS.convert(delegationTokenExpiryCheckIntervalMs, TimeUnit.MILLISECONDS);
            queue.scheduleDeferred(SWEEP_EXPIRED_DELEGATION_TOKENS,
                new EarliestDeadlineFunction(delayNs), event);
        }
    }
Append records to the Raft log. They will be written out asynchronously.

@param log                   The log4j logger.
@param result                The controller result we are writing out.
@param maxRecordsPerBatch    The maximum number of records to allow in a batch.
@param appender              The callback to invoke for each batch. The arguments are last
                             write offset, record list, and the return result is the new
                             last write offset.
@return                      The final offset that was returned from the Raft layer.
metadata/src/main/java/org/apache/kafka/controller/QuorumController.java