content_entity_example I'm studying the content_entity_example module and there are some things I'd like to understand better.
In the file content_entity_example.routing.yml there is this block:

entity.content_entity_example_contact.collection:
   path: '/content_entity_example_contact/list'
   defaults:
   # Calls the list controller, defined in the annotation of the contact entity.
     _entity_list: 'content_entity_example_contact'
     _title: 'Contact list'
   requirements:
   # Checks for permission directly.
     _permission: 'view contact entity'


This is the routing path that shows the contact list, but I did not understand what it means

_entity_list: 'content_entity_example_contact'

Examples are avaiable

The examples are available at this link:
Drupal 8 examples
As the comment states, it looks at the defined entity (Contact) and checks the value of the annotation in Contact.php which is Drupal\content_entity_example\Entity\Controller\ContactListBuilder to see what its entity list builder class is. It knows this because content_entity_example_contact resolves to the class, because it has an id annotation defining it as such.

See: https://cgit.drupalcode.org/examples/tree/content_entity_example/src/Entity/Contact.php