In order to reuse code, I need to be able to customise component parameters dialogs

Essentials uses the generic EssentialsDocumentComponent for its "Banner" catalog component. When you drag and drop a new Banner component instance into an HST container, the component's parameters dialog allows you to select any kind of document, not just a Banner document. That's because we use the generic HST component, which is annotated with a generic ParametersInfo class to control the parameters dialog.

In order to avoid subclassing these generic classes just to restrict the JcrPath picker to Banner documents, there should be a way to configure that the JcrPath picker of the Banner catalog component (and all instantiations thereof) should be limited to Banner documents only.

In a wider sense, there should be a mechanism how a catalog component can configure the parameters dialog behaviour of its instances.