WordPress at a glance
action is not described

action_scheduler/migration_complete action-hook . WC 1.0

Usage

add_action( 'action_scheduler/migration_complete', 'action_function_name_8692' );
function action_function_name_8692(){
	// action...
}

Where the hook is called

Scheduler::mark_complete()
action_scheduler/migration_complete
woocommerce/packages/action-scheduler/classes/migration/Scheduler.php 57
do_action( 'action_scheduler/migration_complete' );

Where in WP core the hook is used WooCommerce

woocommerce/packages/action-scheduler/classes/abstracts/ActionScheduler.php 184
add_action( 'action_scheduler/migration_complete', 'ActionScheduler_WPCommentCleaner::maybe_schedule_cleanup' );