The max = 1 constraint does not allow for shared ownership of tasks (for,example between a Practitioner and the practitioner's organization.  DaVinci CDex has encountered this issue when trying to reference both the provider individual and the organization for fulfilling an attachment request.

Proposal is to change the Task.owner from max = 1 to max = *

and update the comment to say:

"Task ownership may be shared. For example, the owner can reference both a practitioner and the practitioner's organization"