* href="http://en.wikipedia.org/wiki/Null_Object_pattern">null object</a> for the type in question.
 *
 * <p>This class is not intended as a direct analogue of any existing "option" or "maybe" construct
 * from other programming environments, though it may bear some similarities.
 *
 * <p>An instance of this class is serializable if its reference is absent or is a serializable
 * object.
 *

		h.ID, _ = h.disk.GetDiskID()
		h.PoolIndex, h.SetIndex, h.DiskIndex = h.disk.GetDiskLoc()
	}
	h.mu.Unlock()
	return h.save(ctx)
}

// save will unconditionally save the tracker and will be created if not existing.
func (h *healingTracker) save(ctx context.Context) error {
	h.mu.Lock()
	if h.PoolIndex < 0 || h.SetIndex < 0 || h.DiskIndex < 0 {
		// Attempt to get location.
		if api := newObjectLayerFn(); api != nil {

*   The admission webhook configurations API, part of the admissionregistration API, is now at v1beta1. Delete any existing webhook configurations before you upgrade, and update your configuration files to use the latest API. For this and the previous...

    List<V> oldValues = getCopy(key);
    ListIterator<V> keyValues = new ValueForKeyIterator(key);
    Iterator<? extends V> newValues = values.iterator();

    // Replace existing values, if any.
    while (keyValues.hasNext() && newValues.hasNext()) {
      keyValues.next();
      keyValues.set(newValues.next());
    }

    // Remove remaining old values, if any.

			diffSlc := getMissingSiteNames(currDeploymentIDsSet, deploymentIDsSet, currSites.Sites)
			return madmin.ReplicateAddStatus{}, errSRInvalidRequest(fmt.Errorf("all existing replicated sites must be specified - missing %s", strings.Join(diffSlc, " ")))
		}
	}

	// validate that all clusters are using the same IDP settings.
	err = c.validateIDPSettings(ctx, sites)
	if err != nil {

          <executions>
            <!--
            We can apparently have only one <jdk> per execution: Others are silently ignored :(
            To properly test this, you need to remove existing toolchains:
            rm -rf ~/.m2/jdks/ ~/.m2/toolchains.xml
            (But don't run that if you have put something into ~/.m2/toolchains.xml yourself.)
            -->
            <execution>

          <executions>
            <!--
            We can apparently have only one <jdk> per execution: Others are silently ignored :(
            To properly test this, you need to remove existing toolchains:
            rm -rf ~/.m2/jdks/ ~/.m2/toolchains.xml
            (But don't run that if you have put something into ~/.m2/toolchains.xml yourself.)
            -->
            <execution>

		result.HealthyRead = result.HealthyRead && drivesHealing == 0
		result.HealingDrives = drivesHealing
	}

	return result
}

// PutObjectMetadata - replace or add tags to an existing object
func (z *erasureServerPools) PutObjectMetadata(ctx context.Context, bucket, object string, opts ObjectOptions) (ObjectInfo, error) {
	object = encodeDirObject(object)
	if z.SinglePool() {

CSI Migration enables the replacement of existing in-tree storage plugins such as `kubernetes.io/gce-pd` or `kubernetes.io/aws-ebs` with a corresponding CSI driver.
If CSI Migration is working properly, Kubernetes end users shouldn’t notice a difference.
After migration, Kubernetes users may continue to rely on all the functionality of in-tree storage plugins using the existing interface.

        if (existingCounter == null) {
          return 0;
        }
        // existingCounter != null: fall through to operate against the existing AtomicInteger
      }

      while (true) {
        int oldValue = existingCounter.get();
        if (oldValue != 0) {
          try {
            int newValue = Math.addExact(oldValue, occurrences);