Issue #3223811: Support migrate content with its translations

modules/migrate_drupal_d8_definition_export/src/Commands/MigrateDrupalD8DefinitionExportCommands.php

+<?php
+
+namespace Drupal\migrate_drupal_d8_definition_export\Commands;
+
+use Drupal\Core\Entity\EntityFieldManagerInterface;
+use Drush\Commands\DrushCommands;
+use Drupal\field\Entity\FieldConfig;
+use Drush\Drush;
+
+/**
+ * Export definitions.
+ *
+ * For example translatable fields.
+ */
+class MigrateDrupalD8DefinitionExportCommands extends DrushCommands {
+
+  /**
+   * Entity field manager.
+   *
+   * @var \Drupal\Core\Entity\EntityFieldManagerInterface
+   */
+  private $entityFieldManager;
+
+  /**
+   * Construct.
+   *
+   * @param \Drupal\Core\Entity\EntityFieldManagerInterface $entity_field_manager
+   *   Entity field manager.
+   */
+  public function __construct(EntityFieldManagerInterface $entity_field_manager) {
+    $this->entityFieldManager = $entity_field_manager;
+  }
+
+  /**
+   * Export field definitions.
+   *
+   * @param array $options
+   *   An associative array of options.
+   *
+   * @option entity_type
+   *  Entity type.
+   * @option bundle
+   *  Bundle.
+   * @option properties
+   *  A list of properties.
+   *
+   * @command d8_definition:export
+   * @aliases d8-d:export
+   * @usage drush d8-d:export --entity_type=node --bundle=product --properties=translatable > /tmp/test.json
+   * Export the property translatable from node of type product
+   * to the file test.json.
+   */
+  public function export(array $options = [
+    'entity_type' => '',
+    'bundle' => '',
+    'properties' => '',
+  ]) {
+    $definition = $this->entityFieldManager->getFieldDefinitions($options['entity_type'], $options['bundle']);
+    $extract_properties_list = explode(',', $options['properties']);
+    $properties = [];
+    $fields = array_keys($definition);
+    foreach ($fields as $field) {
+      foreach ($extract_properties_list as $property) {
+        if ($definition[$field] instanceof FieldConfig) {
+          $properties[$field][$property] = $definition[$field]->get($property);
+        }
+      }
+    }
+    Drush::output()->write(dt(json_encode($properties, JSON_PRETTY_PRINT)));
+  }
+
+}