Perl's OpenAPI::Client - how to pass additionalProperties in OpenAPI GET query request?

I'm trying to pass filter variables in a GET request to an OpenAPI route with this specification:

  - in: query
    name: params
    schema:
      type: object
      additionalProperties:
        type: string
    style: form
    explode: true       

I've tried various different ways of passing the data at request time:

my $client = OpenAPI::Client->new(...);

my $tx = $client->findApps({
    params => { 'id' =>  '1' }
});

my $tx = $client->findApps({ 'id' =>  '1' });

What is the correct way to do this?