getKey method
Will get a collection of PcoServicesKey objects (expecting one)
using a path like this: https://api.planningcenteronline.com/services/v2/service_types/1/plans/1/items/1/key
Implementation
Future<PcoCollection<PcoServicesKey>> getKey(
{PcoServicesKeyQuery? query}) async {
query ??= PcoServicesKeyQuery();
var url = '$apiEndpoint/key';
return PcoCollection.fromApiCall<PcoServicesKey>(url,
query: query, apiVersion: apiVersion);
}