if (topicNames == null) {
throw new IllegalArgumentException(PUSH_TOPIC_PARAM + " request parameter must be present");
}
session.subscribe(topicNames);
Map<String, Object> subscriptionData = new HashMap<String, Object>(4);
subscriptionData.put("sessionId", session.getId());
Map<TopicKey, String> failedSubscriptions = session.getFailedSubscriptions();