setRevisionMetadataKey example

  public function entityTypeBuild(array &$entity_types) {
    foreach ($entity_types as $entity_type) {
      if ($this->workspaceManager->isEntityTypeSupported($entity_type)) {
        $entity_type->addConstraint('EntityWorkspaceConflict');
        $entity_type->setRevisionMetadataKey('workspace', 'workspace');
      }
    }
  }

  /** * Removes the 'latest-version' link template provided by Content Moderation. * * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_types * An array of entity types. * * @see hook_entity_type_alter() */

    // If the entity type is no longer supported by Workspaces, remove the     // revision metadata field.     if ($this->workspaceManager->isEntityTypeSupported($original) && !$this->workspaceManager->isEntityTypeSupported($entity_type)) {
      $revision_metadata_keys = $original->get('revision_metadata_keys');
      $field_storage_definition = $this->entityLastInstalledSchemaRepository->getLastInstalledFieldStorageDefinitions($entity_type->id())[$revision_metadata_keys['workspace']];
      $this->entityDefinitionUpdateManager->uninstallFieldStorageDefinition($field_storage_definition);

      // We are only removing a revision metadata key so we don't need to go       // through the entity update process.       $entity_type->setRevisionMetadataKey('workspace', NULL);
      $this->entityLastInstalledSchemaRepository->setLastInstalledDefinition($entity_type);
    }
  }

  /** * {@inheritdoc} */
  public function onFieldableEntityTypeUpdate(EntityTypeInterface $entity_type, EntityTypeInterface $original, array $field_storage_definitions, array $original_field_storage_definitions, array &$sandbox = NULL) {
    $this->onEntityTypeUpdate($entity_type, $original);
  }