@OnOpen
public void open(Session session) {
peers.add(session);
Tweet tweet = new Tweet();
tweet.setAuthor("THE SERVER");
tweet.setMessage("Welcome! We will provide you with data " + "as soon as we have it available");
List<Tweet> tweets = Arrays.asList(tweet);
session.getAsyncRemote().sendText(Tweet.listToJsonArray(tweets).toString());
logger.info("opened session with id " + session.getId());
}