/**
     * Sets the authenticator used to respond to challenges from origin servers. Use
     * [proxyAuthenticator] to set the authenticator for proxy servers.
     *
     * If unset, the [no authentication will be attempted][Authenticator.NONE].
     */
    fun authenticator(authenticator: Authenticator) =
      apply {
        this.authenticator = authenticator
      }

## Version 3.4.2

_2016-11-03_

 *  Fix: Recover gracefully when an HTTP/2 connection is shutdown. We had a
    bug where shutdown HTTP/2 connections were considered usable. This caused
    infinite loops when calls attempted to recover.


## Version 3.4.1

_2016-07-10_

 *  **Fix a major bug in encoding HTTP headers.** In 3.4.0 and 3.4.0-RC1 OkHttp
    had an off-by-one bug in our HPACK encoder. This bug could have caused the

		// to attempt a heal on the object.
		if countErrs(errs, errDiskNotFound) > 0 {
			return
		}

		var missingBlocks int
		for i := range errs {
			if IsErr(errs[i],
				errFileNotFound,
				errFileVersionNotFound,
				errFileCorrupt,
			) {
				missingBlocks++
			}
		}

		// if missing metadata can be reconstructed, attempt to reconstruct.

	})

	// initialize the object layer.
	defer setObjectLayer(z)

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	attempt := 1
	for {
		var err error
		bootstrapTrace(fmt.Sprintf("poolMeta.Init: loading pool metadata, attempt: %d", attempt), func() {
			err = z.Init(ctx) // Initializes all pools.
		})
		if err != nil {
			if !configRetriableErrors(err) {

	}
	return time.Unix(0, x.versions[0].header.ModTime)
}

func (x *xlMetaV2) addVersion(ver xlMetaV2Version) error {
	modTime := ver.getModTime().UnixNano()
	if !ver.Valid() {
		return errors.New("attempted to add invalid version")
	}
	encoded, err := ver.MarshalMsg(nil)
	if err != nil {
		return err
	}

	// returns error if we have exceeded configured object max versions

                if (attempt % 10 == 0 || attempt < 5) {
                    log.debug("Server not ready yet (attempt {}): {}", attempt + 1, e.getMessage());
                }
                // Use exponential backoff for more efficient waiting
                if (attempt < 10) {
                    Thread.sleep(500); // First 10 attempts: 0.5 second intervals
                } else if (attempt < 30) {

	if err != nil {
		return err
	}

	wk, err := workers.New(workerSize)
	if err != nil {
		// invalid worker size.
		return err
	}

	retry := false
	for attempts := 1; attempts <= retryAttempts; attempts++ {
		attempts := attempts
		// one of source/target is s3, skip delete marker and all versions under the same object name.

   *
   * <p>The returned {@code Future} attempts to keep its cancellation state in sync with that of the
   * input future and that of the future returned by the chain function. That is, if the returned
   * {@code Future} is cancelled, it will attempt to cancel the other two, and if either of the
   * other two is cancelled, the returned {@code Future} will receive a callback in which it will
   * attempt to cancel itself.
   *

	if err := store.saveUserIdentity(ctx, cred.AccessKey, userType, ui); err != nil {
		return err
	}

	return cache.updateUserWithClaims(cred.AccessKey, ui)
}

// LoadUser - attempts to load user info from storage and updates cache.
func (store *IAMStoreSys) LoadUser(ctx context.Context, accessKey string) error {
	groupLoad := env.Get("_MINIO_IAM_GROUP_REFRESH", config.EnableOff) == config.EnableOn

        @Override
        public void onRegistrationExpired(WitnessRegistration registration) {
            log.warn("Witness registration expired: {}", registration.getRegistrationId());
            // Could attempt re-registration here
        }
    }

    /**
     * Handle a witness event
     *
     * @param notification the witness notification
     */