I tripped up over this today and wasted too much time so for my own reference
In the controller CamelCaseController.php :
class CamelCaseController extends ControllerBase
{
...
}
In the views directory:
A sub-directory named "camel_case" that contains views that relate to actions.
In Security.php:
$adminResources = [
'camel_case' => ['index', 'save']
];
In routes:
$router->add("/admin/camelcase[/]{0,1}", "backend::camel_case::index");
//or
$router->add("/admin/camelcase[/]{0,1}",
[
"module" => "backend",
"controller" => "camel_case",
"action" => "index"
]
);