The Gantt chart control itself doesn't really have any requirements for a model. It is simply providing convenience methods for the underlying controls (tree table view, graphics view). The following table lists the relevant methods:

Method Description
void setRoot(R row);
R getRoot();
Sets / gets the root node for the underlying tree table view control.
ObservableList<Layer> getLayers();
The list of layers that will be displayed by the graphics view.
ObservableList<ActivityLink<?>> getLinks();
The list of links that will be displayed by the graphics view.
ObservableList<Calendar<?>> getCalendars();
The list of calendars that will be displayed by the graphics view.