Unable to specify Startup Disk for Policy

[cybertunnel]

Options provided by documentation:

RESTART_DISKS =

    {
      current: 'Current Startup Disk',
      selected: 'Currently Selected Startup Disk (No Bless)',
      netboot: 'NetBoot',
      os_installer: 'inPlaceOSUpgradeDirectory'
    }.freeze

The problem is, there currently is no way of being able to specify the restart disk since when specifying the disk it switches over to specify_startup function instead.

Desired outcome:
policy.startup_disk = :current or policy.startup_disk = 'Current Startup Disk' where it also empties the :specify_startup reboot value as well.