Menu links migrate example: import main-menu links which associated with article and page content type.

migrate_plus.migration.my_group_d7_menu_links.yml

# Migration configuration for main menu links.
langcode: en
status: true
dependencies: {  }
id: my_group_d7_menu_links
class: Drupal\migrate\Plugin\Migration
field_plugin_method: null
cck_plugin_method: null
migration_tags:
  - 'Drupal 7'
  - Content
  - 'Main menu links'
migration_group: my_group
label: 'Menu links'
source:
  plugin: menu_link
  constants:
    entity_prefix: 'entity:'
    node_prefix: 'node/'
process:
  title: link_title
  description: description
  # Migrate menu links from main menu only.
  menu_name:
    -
      plugin: get
      source: menu_name
    -
      plugin: skip_on_value
      not_equals: true
      method: row
      value:
        - main-menu
    -
      plugin: static_map
      bypass: true
      source: menu_name
      map:
        main-menu: main
  # In this process pipeline, given a menu link path that might be for a
  # translated node which has been merged with the default language node, we are
  # trying to determine the new node ID, that is the ID of the default language
  # node.
  new_nid:
    -
      # If the path is of the form "node/<ID>" and is not routed, we will get
      # back an URI of the form "base:node/<ID>".
      plugin: link_uri
      source: link_path
      validate_route: false
    -
      # Isolate the node ID.
      plugin: explode
      delimiter: 'base:node/'
    -
      # Extract the node ID.
      plugin: extract
      default: false
      index:
        - 1
    -
      # Skip row if node ID is empty.
      plugin: skip_on_empty
      method: row
    -
      # With the old node ID in hand, lookup in the necessary nodes mapping
      # tables to find the new node ID.
      plugin: migration_lookup
      migration:
        - my_group_d7_node_article
        - my_group_d7_node_page
      no_stub: true
    -
      # Skip row if the new node ID is empty.
      plugin: skip_on_empty
      method: row
  # This will be used in the "link/uri" and "route" processes below.
  link_path:
    plugin: concat
    source:
      - 'constants/node_prefix'
      - '@new_nid'
  link/uri:
    plugin: concat
    source:
      - 'constants/entity_prefix'
      - '@link_path'
  link/options:
    -
      plugin: get
      source: options
  route:
    plugin: route
    source:
      - '@link_path'
      - options
  route_name: '@route/route_name'
  route_parameters: '@route/route_parameters'
  url: '@route/url'
  options: '@route/options'
  external: external
  weight: weight
  expanded: expanded
  enabled: enabled
  parent:
    plugin: menu_link_parent
    source:
      - plid
      - '@menu_name'
      - parent_link_path
  changed: updated
destination:
  plugin: entity:menu_link_content
  default_bundle: menu_link_content
  no_stub: true
migration_dependencies:
  optional:
    - my_group_d7_node_article
    - my_group_d7_node_page