drupalcampbristol/core/modules/block_content/block_content.links.task.yml

entity.block_content.collection:
  title: 'Custom block library'
  route_name: entity.block_content.collection
  base_route: block.admin_display
block_content.list_sub:
  title: Blocks
  route_name: entity.block_content.collection
  parent_id: entity.block_content.collection
entity.block_content_type.collection:
  title: Block types
  route_name: entity.block_content_type.collection
  parent_id: entity.block_content.collection
  weight: 1

entity.block_content.canonical:
  title: Edit
  route_name: entity.block_content.canonical
  base_route: entity.block_content.canonical
entity.block_content.delete_form:
  title: Delete
  route_name: entity.block_content.delete_form
  base_route: entity.block_content.canonical

# Default tab for custom block type editing.
entity.block_content_type.edit_form:
  title: 'Edit'
  route_name: entity.block_content_type.edit_form
  base_route: entity.block_content_type.edit_form