Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / vendor / chi-teck / drupal-code-generator / templates / d8 / plugin / views / style-schema.twig

views.style.{{ plugin_id }}:
  type: views_style
  label: '{{ plugin_label }}'
  mapping:
    wrapper_class:
      type: string
      label: Wrapper class