org-icalendar-use-deadline

org-icalendar-use-deadline is a variable defined in `ox-icalendar.el'.
Its value is

(event-if-not-todo todo-due)

Documentation:
Contexts where iCalendar export should use a deadline time stamp.

This is a list with several symbols in it. Valid symbol are:
`event-if-todo' Deadlines in TODO entries become calendar events.
`event-if-not-todo' Deadlines in non-TODO entries become calendar events.
`todo-due' Use deadlines in TODO entries as due-dates

You can customize this variable.