How to produce markup from a custom views field (FieldPluginBase based) render method in D8? I've created a custom views field following the excelent Creating a custom Views field in Drupal 8 guide. The render method returns the desired output, except that it's being sanitized somewhere down the line and thus the html markup comes out as plain text on the page.

I'd rather put the html markup into the theme, but there doesn't seem to be such thing as 

views-view-field-&lt;fieldname&gt;.html.twig

in Drupal8 ?
I can output HTML using my render method. Take a look:

  /**
   * {@inheritdoc}
   */
  public function render(ResultRow $values) {

    $field_abnormal_category = $this-&gt;view-&gt;field['field_abnormal_category']-&gt;original_value-&gt;__toString();

    if($field_abnormal_category == 'No') {
      $field_category_image = $this-&gt;view-&gt;field['field_category_image']-&gt;original_value-&gt;__toString();
    }
    else {
      $field_category_image = '';
    }

    return [
    '#type' =&gt; 'inline_template',
    '#template' =&gt; $field_category_image
    ];

  }