Issue #3276035 by kim.pepper: Inform users that 9200 is the default port

    $form['url'] = [

      '#type' => 'url',

      '#title' => $this->t('OpenSearch URL'),

      '#description' => $this->t('The URL of your OpenSearch server, e.g. <code>http://127.0.0.1</code> or <code>https://www.example.com:443</code>. <strong>Do not include a trailing slash.</strong>'),

      '#description' => $this->t('The URL of your OpenSearch server, e.g. <code>http://127.0.0.1:9200</code> or <code>https://www.example.com:443</code>. The port defaults to <code>9200</code> if not specified. <strong>Do not include a trailing slash.</strong>'),

      '#default_value' => $this->configuration['url'] ?? '',

      '#required' => TRUE,

    ];