Create unordered list in render array

Question

I'm attempting to create an unordered list using a render array in a custom block in a custom module.

I understand if I wanted to wrap things in div I could always use the 'container' type. Like so

    $content = [
        'container'    => [
            '#type'       => 'container',
            '#attributes' => [
                'class'      => ['container'],
            ],
            'item 1'      => [
                '#type'       => 'html_tag',
                '#tag'        => 'p',
                '#value'      => 'Item 1',
            ],
            'item 2'      => [
                '#type'       => 'html_tag',
                '#tag'        => 'p',
                '#value'      => 'Item 2',
            ],
        ],
    ];

But I'd like to be able to use an unordered list like so

    $content = [
        'container'    => [
            '#type'       => 'html_tag',
            '#attributes' => [
                'class'      => ['container'],
            ],
            '#tag' => 'ul',
            'item 1'      => [
                '#type'       => 'html_tag',
                '#tag'        => 'li',
                '#value'      => 'Item 1',
            ],
            'item 2'      => [
                '#type'       => 'html_tag',
                '#tag'        => 'li',
                '#value'      => 'Item 2',
            ],
        ],
    ];

What I'd like that to produce is

<ul class="container">
  <li>Item 1</li>
  <li>Item 2</li>
</ul>

But instead it produces

<ul class="container"></ul>
<li>Item 1</li>
<li>Item 2</li>   

Is there a way to create an unordered list using render arrays?

Answer 1

Use the theme 'item_list':

$content = [
  '#theme' => 'item_list',
  '#list_type' => 'ul',
  '#title' => 'My List',
  '#items' => ['item 1', 'item 2'],
  '#attributes' => ['class' => 'mylist'],
  '#wrapper_attributes' => ['class' => 'container'],
];          

The wrapper_attributes are not used in all themes. In core this is classy and bartik, which is based on classy.