func (t *Transition) UnmarshalXML(d *xml.Decoder, startElement xml.StartElement) error {
	type transitionWrapper Transition
	var trw transitionWrapper
	err := d.DecodeElement(&trw, &startElement)
	if err != nil {
		return err
	}
	*t = Transition(trw)
	t.set = true
	return nil
}

// Validate - validates the "Transition" element
func (t Transition) Validate() error {
	if !t.set {

}

// ExpectedExpiryTime calculates the expiry, transition or restore date/time based on a object modtime.
// The expected transition or restore time is always a midnight time following the object
// modification time plus the number of transition/restore days.
//
//	e.g. If the object modtime is `Thu May 21 13:42:50 GMT 2020` and the object should
//	    transition in 1 day, then the expected transition time is `Fri, 23 May 2020 00:00:00 GMT`

Lifecycle transition rules can be applied to buckets (both versioned and un-versioned) by specifying the tier name defined above as the transition storage class for the lifecycle rule.

## Implementation

   *
   * <p>The ordering of the {@link State} enum is defined such that if there is a state transition
   * from {@code A -> B} then {@code A.compareTo(B) < 0}. N.B. The converse is not true, i.e. if
   * {@code A.compareTo(B) < 0} then there is <b>not</b> guaranteed to be a valid state transition
   * {@code A -> B}.
   *
   * @since 9.0 (in 1.0 as {@code com.google.common.base.Service.State})
   */

## Add warm tier
./mc ilm tier add minio sitea WARM-TIER --endpoint http://localhost:9006 --access-key minio --secret-key minio123 --bucket bucket

## Add ILM rules
./mc ilm add sitea/bucket --transition-days 0 --transition-tier WARM-TIER --transition-days 0 --noncurrent-expire-days 2 --expire-days 3 --prefix "myprefix" --tags "tag1=val1&tag2=val2"
./mc ilm rule list sitea/bucket

## Check ilm expiry flag
./mc admin replicate info sitea --json

--restore-request Days=3
```

### 4.1 Monitoring transition events

`s3:ObjectTransition:Complete` and `s3:ObjectTransition:Failed` events can be used to monitor transition events between the source cluster and transition tier. To watch lifecycle events, you can enable bucket notification on the source bucket with `mc event add`  and specify `--event ilm` flag.

Note that transition event notification is a MinIO extension.

## Explore Further

	ilmTransitionActiveTasksMD          = NewGaugeMD(transitionActiveTasks, "Number of active ILM transition tasks")
	ilmTransitionPendingTasksMD         = NewGaugeMD(transitionPendingTasks, "Number of pending ILM transition tasks in the queue")
	ilmTransitionMissedImmediateTasksMD = NewCounterMD(transitionMissedImmediateTasks, "Number of missed immediate ILM transition tasks")

		err   error
	}{
		{
			input: `<Transition>
			<Days>0</Days>
			<StorageClass>S3TIER-1</StorageClass>
		  </Transition>`,
			err: nil,
		},
		{
			input: `<Transition>
			<Days>1</Days>
			<Date>2021-01-01T00:00:00Z</Date>
			<StorageClass>S3TIER-1</StorageClass>
		  </Transition>`,
			err: errTransitionInvalid,
		},
		{
			input: `<Transition>
			<Days>1</Days>
		  </Transition>`,

      }

      /** Transition to the COMPLETED state and set the value. */
      boolean set(@Nullable V v) {
        return complete(v, null, COMPLETED);
      }

      /** Transition to the COMPLETED state and set the exception. */
      boolean setException(Throwable t) {
        return complete(null, t, COMPLETED);
      }

      /** Transition to the CANCELLED or INTERRUPTED state. */

			isDelMarker:    true,
			expectedAction: DeleteVersionAction,
		},
		// Should transition immediately when Transition days is zero
		{
			inputConfig:    `<BucketLifecycleConfiguration><Rule><Filter></Filter><Status>Enabled</Status><Transition><Days>0</Days><StorageClass>S3TIER-1</StorageClass></Transition></Rule></BucketLifecycleConfiguration>`,
			objectName:     "foodir/fooobject",