Add mergeIfNotFilled to Illuminate\Foundation\Http\FormRequest ...

[repomic]

Maybe this is not the place, but I think FormRequest is missing mergeIfNotFilled() which could go alongside with mergeIfMissing. This would allow setting default values server-side when FormRequests validates optional fields with the "nullable" validation rule.

/**
 * Merge new input into the request's input, but only when that key is not filled from the request.
 *
 * @param  array  $input
 * @return $this
 */
public function mergeIfNotFilled(array $input)
{
    return $this->merge((new Collection($input))
        ->filter(fn ($value, $key) => $this->isNotFilled($key))
        ->toArray()
    );
}