Users can be allocated for resource plans on company holidays.
Schedule records should be set to type = Time off.
In the 'Child Schedule' related list, holiday schedule type should be Exclude not Include. Set the system property 'com.snc.resource_management.exclude_events_from_schedule' to Time Off, and ensure the schedule entries are set to this as well. Now, when trying to allocate user for Christmas, they see the message 'Error Message Cannot create Requested Allocations as there are no working days in the schedule for the plan date range'.