Default parameter for methods in routing type resource Laravel 8

I'm trying to add default parameter to resource routing as per documentation:

My code looks like:

Route::resource('flats', FlatsController::class)->parameters([
    'index' => 'test_parameter',
    'create' => 'test_parameter1',
    'update' => 'test_parameter2'
]);

But unfortunately all the time when listing the routing it gets like in the screenshot below:

Please help guide at what point do I make a mistake?

You have the following:

| Methods   | route                               |
|-----------|-------------------------------------|
| POST      | panel/investments/flats             |
| GET/HEAD  | panel/investments/flats             |
| GET/HEAD  | panel/investments/flats/create      |
| GET/HEAD  | panel/investments/flats/{flat}      |
| PUT/PATCH | panel/investments/flats/{flat}      |
| DELETE    | panel/investments/flats/{flat}      |
| GET/HEAD  | panel/investments/flats/{flat}/edit |

Since the only parameter is {flat} you can only rename this one as per docs:

Route::resource('flats', FlatsController::class)->parameters([
    'flat' => 'apartment'
]);

This results in:

| Methods   | route                                    |
|-----------|------------------------------------------|
| POST      | panel/investments/flats                  |
| GET/HEAD  | panel/investments/flats                  |
| GET/HEAD  | panel/investments/flats/create           |
| GET/HEAD  | panel/investments/flats/{apartment}      |
| PUT/PATCH | panel/investments/flats/{apartment}      |
| DELETE    | panel/investments/flats/{apartment}      |
| GET/HEAD  | panel/investments/flats/{apartment}/edit |