Drupal 8 text filter plugin to remove blank headings

FilterBlankHeadings.php

<?php

namespace Drupal\MY_MODULE\Plugin\Filter;

use Drupal\filter\Plugin\FilterBase;
use Drupal\filter\FilterProcessResult;

/**
 * @Filter(
 *   id = "filter_blank_headings",
 *   title = @Translation("Remove blank heading elements"),
 *   description = @Translation("ckeditor can create a lot of e.g., <code>&lt;h2&gt;&amp;nbsp;&lt;/h2&gt;</code> tags; this removes them"),
 *   type = Drupal\filter\Plugin\FilterInterface::TYPE_MARKUP_LANGUAGE,
 * )
 */
class FilterBlankHeadings extends FilterBase {
  public function process($text, $langcode) {
    $text = trim($text);
    // ugh, unicode
    $text = str_replace(chr(194).chr(160), ' ', $text);
    $text = preg_replace('/<h[2-6].*>(\s|&nbsp;)*<\/h[2-6]>/', '', $text);
    return new FilterProcessResult($text);
  }
}