WP_REST_Request::get_json_params() Parsing null as Zero

Why do I get 0 when WP_REST_Request::get_json_params() parses a JSON body value of null?

I have a method which is responsible for turning a WP_REST_Request into another format which is acceptable for my business logic.

function prepare_item_for_database(WP_REST_Request $request): array
{
    $payload = $request->get_json_params();
    // ... validation
    return $payload;
}

When I have a request which includes null values, the WP_REST_Request::get_json_params() function creates PHP 0, instead of null. I get the following.

Why do I get 0 in the PHP array, instead of null?

HTTP POST Body

{
    "name": "s",
    "feature_id": null,
    "note_id": null
}

PHP Parsed Value

// What I get
Array
(
    [name] => s
    [feature_id] => 0
    [note_id] => 0
)

// What I expect
Array
(
    [name] => s
    [feature_id] => null
    [note_id] => null
)

The schema for the endpoint is like the following

[
    'properties' => [
        'name'  => [
            'type' => 'string'
        ],
        'feature_id' => [
            'type' => 'integer'
        ],
        'note_id' => [
            'type' => 'integer'
        ],
    ]
];