pm-4.1.x-dev/modules/pm_sub_task/pm_sub_task.links.menu.yml

entity.pm_sub_task.collection:
  title: 'Sub Task'
  route_name: entity.pm_sub_task.collection
  parent: pm.admin.content_items
  description: ''
  weight: -15

entity.pm_sub_task_type.collection:
  title: 'Sub Task types'
  parent: pm.admin.content_settings
  route_name: entity.pm_sub_task_type.collection
  weight: -14