isModeratedEntityEditForm example

  public function entityPrepareForm(EntityInterface $entity, $operation, FormStateInterface $form_state) {
    /** @var \Drupal\Core\Entity\EntityFormInterface $form_object */
    $form_object = $form_state->getFormObject();

    if ($this->isModeratedEntityEditForm($form_object) && !$entity->isNew()) {
      // Generate a proper revision object for the current entity. This allows       // to correctly handle translatable entities having pending revisions.       /** @var \Drupal\Core\Entity\ContentEntityStorageInterface $storage */
      $storage = $this->entityTypeManager->getStorage($entity->getEntityTypeId());
      /** @var \Drupal\Core\Entity\ContentEntityInterface $new_revision */
      $new_revision = $storage->createRevision($entity, FALSE);

      // Restore the revision ID as other modules may expect to find it still       // populated. This will reset the "new revision" flag, however the entity       // object will be marked as a new revision again on submit.       // @see \Drupal\Core\Entity\ContentEntityForm::buildEntity()