/// <summary>
/// Unsubscribes change events for all state variables of this service.
/// </summary>
/// <exception cref="IllegalCallException">If the state variables are not subscribed
/// (see <see cref="IsStateVariablesSubscribed"/>).</exception>
public void UnsubscribeStateVariables()
{
DeviceConnection connection = _connection;
if (connection == null)
{
throw new IllegalCallException("UPnP service is not connected to a UPnP network service");
}
if (!connection.IsServiceSubscribedForEvents(this))
{
throw new IllegalCallException("State variables are not subscribed");
}
connection.OnUnsubscribeEvents(this);
}