service property
App service.
By default, the task is sent to the service which is the default service when the task is attempted. For some queues or tasks which were created using the App Engine Task Queue API, host is not parsable into service, version, and instance. For example, some tasks which were created using the App Engine SDK use a custom domain name; custom domains are not parsed by Cloud Tasks. If host is not parsable, then service, version, and instance are the empty string.
Implementation
core.String? service;