opencase/opencase.services.yml

services:
  opencase.breadcrumb:
  # The namespace + classname from your BreadcrumbBuilderInterface class
    class: Drupal\opencase\Breadcrumb\BreadcrumbBuilder
    
    # Priority determines the order in which Breadcrumb services run.
    tags:
      - { name: breadcrumb_builder, priority: 100 }