itemIds.addAll(other.itemIds);
itemIds.add(other.itemIds);
        PendingDelete add(PendingDelete other) {            if (other != null) {                size     += other.size;                contacts += other.contacts;                itemIds.addAll(other.itemIds);                unreadIds.addAll(other.unreadIds);                blobs.addAll(other.blobs);            }            return this;        }