Creates a new Assignment, returns the created Assignment. Checks the authorization status, and checks that the chosen type is compatible with the template of the Issue.
Return
the saved created Assignment
Parameters
used to check for the required permission
defines the Issue, User and optional AssignmentType of the Assignment
Creates a new Assignment on an issue at atTime as byUser. Does not check the authorization status. If present, checks that the assignmentType is compatible with the template of the issue. Does neither save the created Assignment nor the issue. It is necessary to save the issue or returned Assignment afterwards.
Parameters
the optional type of the created Assignment, must be compatible with the template of issue
the point in time when the modification happened, updates Issue.lastUpdatedAt if necessary
the User who caused the update, updates Issue.participants if necessary