How do I include a twig file in a custom block type module?

Question

I've created a custom module that creates a jumbotron custom block type. The module has an empty .module file and a dir config/install with many .yml files. This works great when I install and create blocks. I can even place my block--bundle--jumbotron.html.twig in the templates folder of the theme and styling works great! I would like this twig file included in the module and many tutorials explain how to do this if you have a build function in your module, I do not. The module is just creating a block type for me.

Answer 1

Create a theme hook with the template name by replacing dashes with underscores:

mymodule.module:

/**
 * Implements hook_theme().
 */
function mymodule_theme() {
  return [
    'block__bundle__jumbotron' => [
      'render element' => 'elements',
      'base hook' => 'block',
    ],
  ];
}