Project: mesos
Issue MESOS-4382: Change the `principal` in `ReservationInfo` to optional
With the addition of HTTP endpoints for {{/reserve}} and {{/unreserve}}, it is now desirable to allow dynamic reservations without a principal, in the case where HTTP authentication is disabled. To allow for this, we will change the {{principal}} field in {{ReservationInfo}} from required to optional. For backwards-compatibility, however, the master should currently invalidate any {{ReservationInfo}} messages that do not have this field set.
Story points: 1