Convert an existing entity type to revisionable

Question

I am trying to make an existing entity type (knowledge), from the Knowledge Project, revisionable. I followed these instructions Converting a content entity type to be revisionable. A new table, knowledge_revision, is not created, and and the fields are added to the knowledge table. I am lost on what to do next.

update code

use Drupal\Core\Field\BaseFieldDefinition;

$definition_update_manager = \Drupal::entityDefinitionUpdateManager();

// Add the published entity key and revisionable metadata fields to the
// knowledge entity type.
$entity_type = $definition_update_manager->getEntityType('knowledge');
$entity_type_id = $entity_type->id();

$revision_metadata_keys = [
  'revision_user' => 'revision_user',
  'revision_created' => 'revision_created',
  'revision_log_message' => 'revision_log_message'
];
$entity_type->set('revision_metadata_keys', $revision_metadata_keys);

$entity_type->set('show_revision_ui', TRUE);

$definition_update_manager->updateEntityType($entity_type);

// Add the revision metadata fields.
$revision_created = BaseFieldDefinition::create('created')
  ->setLabel(t('Revision create time'))
  ->setDescription(t('The time that the current revision was created.'))
  ->setRevisionable(TRUE);
$definition_update_manager->installFieldStorageDefinition('revision_created', $entity_type_id, $entity_type_id, $revision_created);

$revision_user = BaseFieldDefinition::create('entity_reference')
  ->setLabel(t('Revision user'))
  ->setDescription(t('The user ID of the author of the current revision.'))
  ->setSetting('target_type', 'user')
  ->setRevisionable(TRUE);
$definition_update_manager->installFieldStorageDefinition('revision_user', $entity_type_id, $entity_type_id, $revision_user);

$revision_log_message = BaseFieldDefinition::create('string_long')
  ->setLabel(t('Revision log message'))
  ->setDescription(t('Briefly describe the changes you have made.'))
  ->setRevisionable(TRUE)
  ->setDefaultValue('')
  ->setDisplayOptions('form', [
    'type' => 'string_textarea',
    'weight' => 25,
    'settings' => [
      'rows' => 4,
    ],
  ]);
$definition_update_manager->installFieldStorageDefinition('revision_log_message', $entity_type_id, $entity_type_id, $revision_log_message);

Drupal\knowledge\Entity\Knowledge

/**
 * Defines the knowledge entity class.
 *
 * @ContentEntityType(
 *   id = "knowledge",
 *   label = @Translation("Knowledge"),
 *   label_singular = @Translation("knowledge"),
 *   label_plural = @Translation("knowledge"),
 *   label_count = @PluralTranslation(
 *     singular = "@count knowledge",
 *     plural = "@count knowledge",
 *   ),
 *   bundle_label = @Translation("Knowledge type"),
 *   handlers = {
 *     "storage" = "Drupal\knowledge\KnowledgeStorage",
 *     "storage_schema" = "Drupal\knowledge\KnowledgeStorageSchema",
 *     "access" = "Drupal\knowledge\KnowledgeAccessControlHandler",
 *     "list_builder" = "Drupal\Core\Entity\EntityListBuilder",
 *     "view_builder" = "Drupal\knowledge\KnowledgeViewBuilder",
 *     "views_data" = "Drupal\knowledge\KnowledgeViewsData",
 *     "form" = {
 *       "default" = "Drupal\knowledge\KnowledgeForm",
 *       "delete" = "Drupal\knowledge\Form\DeleteForm",
 *       "unlink" = "Drupal\knowledge\Form\UnlinkForm",
 *     },
 *   },
 *   base_table = "knowledge",
 *   revision_table = "knowledge_revision",
 *   show_revision_ui = TRUE,
 *   uri_callback = "knowledge_uri",
 *   translatable = FALSE,
 *   entity_keys = {
 *     "id" = "kid",
 *     "bundle" = "knowledge_type",
 *     "uuid" = "uuid",
 *     "published" = "status",
 *     "owner" = "uid",
 *     "revision" = "revision_id",
 *   },
 *   revision_metadata_keys = {
 *     "revision_user" = "revision_user",
 *     "revision_created" = "revision_created",
 *     "revision_log_message" = "revision_log_message",
 *   },
 *   links = {
 *     "canonical" = "/knowledge/{knowledge}",
 *     "delete-form" = "/knowledge/{knowledge}/delete",
 *     "delete-multiple-form" = "/admin/content/knowledge/delete",
 *     "edit-form" = "/knowledge/{knowledge}/edit",
 *     "create" = "/knowledge",
 *     "unlink-form" = "/knowledge/{knowledge}/unlink",
 *   },
 *   bundle_entity_type = "knowledge_type",
 *   field_ui_base_route  = "entity.knowledge_type.edit_form",
 * )
 */
class Knowledge extends EditorialContentEntityBase implements KnowledgeInterface {
 ...
  /**
   * {@inheritdoc}
   */
  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
    /** @var \Drupal\Core\Field\BaseFieldDefinition[] $fields */
    $fields = parent::baseFieldDefinitions($entity_type);
    // $fields += static::publishedBaseFieldDefinitions($entity_type);
    $fields += static::ownerBaseFieldDefinitions($entity_type);

    $fields['kid']->setLabel(t('Knowledge ID'))
      ->setDescription(t('The knowledge ID.'));

    $fields['uuid']->setDescription(t('The knowledge UUID.'));

    $fields['knowledge_type']->setLabel(t('Knowledge Type'))
      ->setDescription(t('The knowledge type.'));

    // Set the default value callback for the status field.
    $fields['status']->setDefaultValueCallback('Drupal\knowledge\Entity\Knowledge::getDefaultStatus');

    $fields['uid']
      ->setDescription(t('The user ID of the knowledge author.'));

    $fields['field_name'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Knowledge field name'))
      ->setRequired(TRUE)
      ->setDescription(t('The field name through which this knowledge was added.'))
      ->setSetting('is_ascii', TRUE)
      ->setSetting('max_length', FieldStorageConfig::NAME_MAX_LENGTH);

    $fields['entity_type'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Entity type'))
      ->setRequired(TRUE)
      ->setRevisionable(TRUE)
      ->setDescription(t('The entity type to which this knowledge is attached.'))
      ->setSetting('is_ascii', TRUE)
      ->setSetting('max_length', EntityTypeInterface::ID_MAX_LENGTH);

    $fields['entity_id'] = BaseFieldDefinition::create('entity_reference')
      ->setLabel(t('Entity ID'))
      ->setDescription(t('The ID of the entity of which this knowledge is a reply.'))
      ->setRevisionable(TRUE)
      ->setRequired(TRUE);

    $fields['incident_type'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Incident type'))
      ->setRequired(TRUE)
      ->setDescription(t('The entity type to which this knowledge is attached.'))
      ->setSetting('is_ascii', TRUE)
      ->setSetting('max_length', EntityTypeInterface::ID_MAX_LENGTH);

    $fields['incident_id'] = BaseFieldDefinition::create('entity_reference')
      ->setLabel(t('Incident Id'))
      ->setDescription(t('The ID of the support case.'))
      ->setDisplayConfigurable('form', TRUE)
      ->setDisplayConfigurable('view', TRUE)
      ->setRequired(TRUE);

    $fields['citation'] = BaseFieldDefinition::create('boolean')
      ->setLabel(t('Citation'))
      ->setDescription(t("The owner linked to another's articled."))
      ->setDisplayConfigurable('form', TRUE)
      ->setDisplayConfigurable('view', TRUE)
      ->setRevisionable(TRUE)
      ->setRequired(TRUE);

    $fields['created'] = BaseFieldDefinition::create('created')
      ->setLabel(t('Created'))
      ->setDescription(t('The time that the knowledge was created.'))
      ->setTranslatable(TRUE);

    $fields['changed'] = BaseFieldDefinition::create('changed')
      ->setLabel(t('Changed'))
      ->setDescription(t('The time that the knowledge was last edited.'))
      ->setRevisionable(TRUE)
      ->setTranslatable(TRUE);

    return $fields;
  }
...
}