InternalLoadPropertiesForItems method
      
Future<ServiceResponseCollection<ServiceResponse> > 
InternalLoadPropertiesForItems(
    
- Iterable<Item> items,
- PropertySet propertySet,
- ServiceErrorHandling errorHandling
Implementation
Future<ServiceResponseCollection<ServiceResponse>>
    InternalLoadPropertiesForItems(Iterable<Item> items,
        PropertySet propertySet, ServiceErrorHandling errorHandling) {
  GetItemRequestForLoad request =
      new GetItemRequestForLoad(this, errorHandling);
  request.ItemIds.AddRange(items);
  request.PropertySet = propertySet;
  return request.Execute();
}