Disabled = "Disabled"
	// TransitionStatus status of transition
	TransitionStatus = "transition-status"
	// TransitionedObjectName name of transitioned object
	TransitionedObjectName = "transitioned-object"
	// TransitionedVersionID is version of remote object
	TransitionedVersionID = "transitioned-versionID"
	// TransitionTier name of transition storage class
	TransitionTier = "transition-tier"
)

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 {

        monitor.leave();
      }
    }

    /**
     * Marks the {@link State} as ready to receive transitions. Returns true if no transitions have
     * been observed yet.
     */
    void markReady() {
      monitor.enter();
      try {
        if (!transitioned) {
          // nothing has transitioned since construction, good.
          ready = true;
        } else {

        monitor.leave();
      }
    }

    /**
     * Marks the {@link State} as ready to receive transitions. Returns true if no transitions have
     * been observed yet.
     */
    void markReady() {
      monitor.enter();
      try {
        if (!transitioned) {
          // nothing has transitioned since construction, good.
          ready = true;
        } else {

}

// 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`

Extra metadata maintained internally in `xl.meta` for a transitioned object

```
...
        "MetaSys": {
          "x-minio-internal-transition-status": "Y29tcGxldGU=",
          "x-minio-internal-transition-tier": "R0NTVElFUjE=",

--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

        // Test max attempts in half-open with failure scenario
        circuitBreaker.trip(); // Open again
        Thread.sleep(1100); // Wait for reset

        // First attempt transitions to HALF_OPEN
        try {
            circuitBreaker.executeWithCircuitBreaker(() -> {
                // Verify we're in HALF_OPEN
                assertEquals(State.HALF_OPEN, circuitBreaker.getState());

        log.info("[{}] Manually resetting circuit breaker to CLOSED", name);
        transitionTo(State.CLOSED);
    }

    /**
     * Manually trip the circuit breaker to open state
     */
    public void trip() {
        log.info("[{}] Manually tripping circuit breaker to OPEN", name);
        transitionTo(State.OPEN);
    }

    /**
     * Get current failure threshold (may be dynamically adjusted)

		return toObjectErr(errMethodNotAllowed, bucket, object)
	}
	// verify that the object queued for transition is identical to that on disk.
	if !opts.MTime.Equal(fi.ModTime) || !strings.EqualFold(opts.Transition.ETag, extractETag(fi.Metadata)) {
		return toObjectErr(errFileNotFound, bucket, object)
	}
	// if object already transitioned, return
	if fi.TransitionStatus == lifecycle.TransitionComplete {
		return nil
	}