tl;dr : When refreshing a REST API definition, import only structures actually used by the imported methods, instead of *all* the structures exposed by the API.

Details : 

When refreshing a consumed REST API definition, using the right-click "Refresh REST API..." context-menu item, you can select which methods will be imported. However, *ALL* the structures exposed by the API are imported, even if you import just a single method. 

This in turn triggers as many warnings as there are "Unused Structure", and we then have the tedious and error prone task of removing said unused structures.

If only the actually used structures of the selected methods were imported, the task would be much easier and less error prone.