features:
  - |
    For instance reservation, the reservation parameter ``affinity`` now
    supports ``True`` and ``None`` and defaults to ``None``

    - ``affinity = True``

        * Blazar picks up the same host for the instances for the reservation.
          Using the reservation flavor, users don't need to set additional
          specs such as "server_group" to schedule the instances to the host.

    - ``affinity = False``

        * Blazar picks up different hosts for the instances for the
          reservation. Using the reservation flavor, users don't need to set
          additional specs such as "server_group" to schedule to the hosts.

    - ``affinity = None`` (default)

        * The picked up hosts can be different or same.

    ``AggregateInstanceExtraSpecsFilter``, ``AggregateMultiTenancyIsolation``,
    or ``ServerGroupAffinityFilte`` is not needed any more for blazar's
    instance reservation.