if (subscriptionInfo == null) {
throw new IllegalArgumentException("SubscriptionInfo must not be null.");
}
// optional subscriptionId (only required to modify an existing subscription)
if (subscriptionId != null) {
setRequestHeader(new CodedUrlHeader(HEADER_SUBSCRIPTIONID, subscriptionId));
}
// optional timeout header
long to = subscriptionInfo.getTimeOut();
if (to != DavConstants.UNDEFINED_TIMEOUT) {
setRequestHeader(new TimeoutHeader(subscriptionInfo.getTimeOut()));