Maybe in the Cookbook, add some example of the task ?

There should be in the documentation also another step on actually using it on a twig, I believe, using the variable "children" in it to explain how it's used / accessed properly in a twig;
It should refer on the documentation that the query_type needs to be created from scratch, as it would appear from my reproduction scenario, and how to do it (QA searched all throughout the doc with Search, almost no references to query_type exist, so we couldn't figure out what a query_type is, until we checked the BDD scenario. At first we were considering it to be a Query equated to Public API's Query objects, but the example given, LocationChildren, didn't match any Query on Public API..);
With this sample configuration straight on my ezplatform.yml file as is, I try to access platformui, and I get the error on apache log: