This might be useful when using conditional operator.
Might also be used in place of the default c'tor for GroupItem.
Add a test for it.
Change-Id: I622e5d3d94f7020dc294cf5bca643c53a0813d8a
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>