Is it possible to implement HotSpots only in Java?
This seems a little odd to give API to setup the HotSpots in Java but not be able to invoke a function in Java.
You need to setup a popup trigger to check if an RMB press has been occurred over hotspot.
See com.cimmetry.vueframe.PopupTrigger and the implementation in VueActionSample.PartCatalogueAction (<AutoVue Installation Folder>\examples\VueActionSample) .
In getPopupName(MouseEvent event) you need to keep track of the last hovered hotspot and you should return the right popup name (your custom action menus).
If user fires one of the RMB menus then the performSubAction() (in your custom action) will be invoked with the sub-action name.