code: public void init(boolean fromBackup) {
          if (!fromBackup && store.isEnabled()) {
              Set<Long> keys = store.loadAllKeys();
              if (keys != null) {
                  long maxId = -1;
                  for (Long key : keys) {
                      QueueItem item = new QueueItem(this, key, null);
                      getItemQueue().offer(item);
                      maxId = Math.max(maxId, key);
                  }
                  idGenerator = maxId + 1;
              }
          }
      }
docs: Initializes the item queue with items from the queue store if the store is enabled and if item queue is not being
  initialized as a part of a backup operation. If the item queue is being initialized as a part of a backup operation then
  the operation is in charge of adding items to a queue and the items are not loaded from a queue store.
  
  @param fromBackup indicates if this item queue is being initialized from a backup operation. If false, the
  item queue will initialize from the queue store. If true, it will not initialize