public TokenRet create() {
TokenRet result;
if (tokens.size() == 0 || tokens.get(last.toString()) == null
|| last.plus(3600000).isBeforeNow()) {
final DateTime now = DateTime.now();
final String token = new UUID().toString();
result = new TokenRet(token, now);
tokens.put(now.toString(), token);
last = now;
if (tokens.size() > SIZE + 2) {