code: @SuppressWarnings("unchecked")
  	@Override
  	public R execute() {
  		logger.fine("Executing [AppEngineGetScalar] command");
  		Property<?, R> property = aggregation.property();
  		GetList<E> command = session.get((Metamodel<E>) property.metamodel().root());
  		
  		if (filters != null) {
  			command.filter(filters.toArray(new Filter<?>[] {}));
  		}
  		
  		if (orders != null) {
  			command.sort(orders);
  		}
  		
  		List<E> entities = command.execute();
  		List<R> list = new ArrayList<R>();
  		
  		for (Object entity : entities) {
  			list.add(property.get(entity));
  		}
  		
  		return aggregation.aggregate(list);
  	}
docs: Executes {@code GetScalar} with {@code AppEngineDatastoreSession}.
  
  @return The result of the specified {@code Aggregation}.