The HistoryMigrationSpec enumerated type defines how vCenter history data will be migrated. vCenter History data includes - Statistics - Events - Tasks
Defines what part of vCenter historical data will be migrated along with core data.
Defines how vCenter history will be migrated. If set to true, vCenter history will be migrated separately after successful upgrade or migration, otherwise it will be migrated along with core data during the upgrade or migration process. If unset, vCenter historical data won’t be deferred and will be migrated along with core data.