getBlockIdsForRevisionIds example

protected function getRemovedBlockIds(EntityInterface $entity) {
    $original_sections = $this->getEntitySections($entity->original);
    $current_sections = $this->getEntitySections($entity);
    // Avoid un-needed conversion from revision IDs to block content IDs by     // first determining if there are any revisions in the original that are not     // also in the current sections.     $current_block_content_revision_ids = $this->getInlineBlockRevisionIdsInSections($current_sections);
    $original_block_content_revision_ids = $this->getInlineBlockRevisionIdsInSections($original_sections);
    if ($unused_original_revision_ids = array_diff($original_block_content_revision_ids, $current_block_content_revision_ids)) {
      // If there are any revisions in the original that aren't in the current       // there may some blocks that need to be removed.       $current_block_content_ids = $this->getBlockIdsForRevisionIds($current_block_content_revision_ids);
      $unused_original_block_content_ids = $this->getBlockIdsForRevisionIds($unused_original_revision_ids);
      return array_diff($unused_original_block_content_ids, $current_block_content_ids);
    }
    return [];
  }

  /** * Handles entity tracking on deleting a parent entity. * * @param \Drupal\Core\Entity\EntityInterface $entity * The parent entity. */