drupal/core/modules/block_content/block_content.install

<?php

/**
 * @file
 * Install, update and uninstall functions for the block_content module.
 */

use Drupal\Core\Field\BaseFieldDefinition;

/**
 * Add 'revision_translation_affected' field to 'block_content' entities.
 */
function block_content_update_8001() {
  // Install the definition that this field had in
  // \Drupal\block_content\Entity\BlockContent::baseFieldDefinitions()
  // at the time that this update function was written. If/when code is
  // deployed that changes that definition, the corresponding module must
  // implement an update function that invokes
  // \Drupal::entityDefinitionUpdateManager()->updateFieldStorageDefinition()
  // with the new definition.
  $storage_definition = BaseFieldDefinition::create('boolean')
    ->setLabel(t('Revision translation affected'))
    ->setDescription(t('Indicates if the last edit of a translation belongs to current revision.'))
    ->setReadOnly(TRUE)
    ->setRevisionable(TRUE)
    ->setTranslatable(TRUE);

  \Drupal::entityDefinitionUpdateManager()
    ->installFieldStorageDefinition('revision_translation_affected', 'block_content', 'block_content', $storage_definition);
}

/**
 * Generalizes the d6_block_content_type and d6_block_content_body_field
 * migrations.
 */
function block_content_update_8002() {
  if (\Drupal::moduleHandler()->moduleExists('migrate')) {
    $config = \Drupal::configFactory();
    $templates = \Drupal::service('migrate.template_storage');

    $migration = $config->getEditable('migrate.migration.d6_block_content_type');
    if ($migration) {
      $template = $templates->getTemplateByName('block_content_type');
      $migration
        ->set('id', $template['id'])
        ->set('label', $template['label'])
        ->set('migration_tags', $template['migration_tags'])
        ->set('source', array_merge($migration->get('source'), $template['source']))
        ->clear('source.constants')
        ->set('process', $template['process'])
        ->save(TRUE);
    }

    $migration = $config->getEditable('migrate.migration.d6_block_content_body_field');
    if ($migration) {
      $template = $templates->getTemplateByName('block_content_body_field');
      $migration
        ->set('id', $template['id'])
        ->set('label', $template['label'])
        ->set('migration_tags', $template['migration_tags'])
        ->set('source', array_merge($migration->get('source'), $template['source']))
        ->clear('source.constants')
        ->set('process', $template['process'])
        ->set('migration_dependencies', $template['migration_dependencies'])
        ->save(TRUE);
    }
  }
}