Field UI integration for entity types are no longer per-bundle, only per-entity type

In Drupal 7, the Field UI supported different paths per-bundle for its "Manage Fields" and "Manage Display" functionality.

function node_entity_info() {
  // Bundles must provide a human readable name so we can create help and error
  // messages, and the path to attach Field admin pages to.
  foreach (node_type_get_names() as $type => $name) {
    $return['node']['bundles'][$type] = array(
      'label' => $name,
      'admin' => array(
        'path' => 'admin/structure/types/manage/%node_type',
        'real path' => 'admin/structure/types/manage/' . str_replace('_', '-', $type),
        'bundle argument' => 4,
        'access arguments' => array('administer content types'),
      ),   
    );   
  }
}

This has moved directly to the entity type's annotation:

/**
 * Defines the node entity class.
 *
 * @EntityType(
 *   id = "node",
 *   label = @Translation("Content"),
 *   // ...
 *   route_base_path = "admin/structure/types/manage/{bundle}"
 */
class Node extends ContentEntityBase implements NodeInterface {
}

In the case of more complex UI paths, like in Comment module where the Comment Field UI was placed at the same level as the Node Field UI, you are able to specify a s "bundle prefix":

/**
 * @EntityType(
 *   id = "comment",
 *   label = @Translation("Comment"),
 *   // …
 *   route_base_path = "admin/structure/types/manage/{bundle}/comment",
 *   bundle_prefix = "comment_node_" * )
 */
class Comment extends ContentEntityBase implements CommentInterface {
}

For a comment bundle named 'article', this would generate a path of admin/structure/types/manage/comment_node_article/comment.