Function rest_availability_service_get_header 

async fn rest_availability_service_get_header<S>(
    __arg0: State<Arc<S>>,
    headers: HeaderMap,
    __arg2: Query<GetHeaderRequest>,
) -> Result<Json<HeaderResponse>, RestError>
where
    S: AvailabilityService + Send + Sync + 'static,

GetHeader - JSON endpoint.

GET /v2/availability/header