Problem with updating collection of associated resources

Hi,

In our project we have a few resources, and one of them is aggregating the rest with the OneToMany relations (per each resource). During the creation (POST) of the main resource we're providing the URIs to the associated resources and eveything works fine (providing zero, one or more links).

The issues apear when we try to update the main resource. While using PATCH, we can modify the collections with associations (add, reduce, remove all), but when we're using PUT, no changes are propagated.

We proceeded with using PUT as the only way to update the resources and prior to 4.3.X version we had a really hacky way to achieve the expected result (using a similar request body structure for POST and PUT which updates the collections), but now it doesn't work.

Please have a look on the sample project and let us know if the setup or assumptions are wrong.