The annotation that is going to be created or is currently selected. In case
the annotation is not yet created, pageIndex is null. In case of items for annotation toolbars used in interaction modes
like NutrientViewer.InteractionMode.INK_ERASER, annotation is null.
The object that can be helpful in implementing custom toolbar.
The list of default items that are shown for this particular annotation.
Whether the screen is in desktop layout.
This callback can be run on individual annotation toolbars to modify their toolbar items.
For more information, see Configuration.annotationToolbarItems