In the Property assignment view of a component to which a group has been added, the group appears in the Composition tab on the left hand side similarly as a component instance appears.

It is currently possible to select a property of the group and select the "TOSCA function" button. However nothing happens when the button is selected:

This story is to add all necessary handling to allow the property value of a group be set in the same way and using the same modal as for a component instance property.