/**
* Used in: SAVE, RETRIEVAL, DELETE
*
* <p>Adds an observer to the list of observers for this operation. When any operation is
* complete, all observers will be triggered (in the order they were added). For retrieval tasks,
* observers are triggered AFTER data is delivered to the RetrievalCallback.
*
* <p>If the operation is canceled before the operation finishes, the observers will not be
* triggered.
*
* @param observer to observe the finishing of this operation.
* @return this for chaining.
*/
public QueryBuilder<T> addObserver(OperationObserver observer) {
query.addObserver(observer);
return this;
}
