if (StringUtils.isBlank(userToRetrieve))
userToRetrieve = jiraUser;
Promise<User> promise = client.getUserClient().getUser(userToRetrieve);
User user = promise.claim();
resp.addHeader("Content-Type", "text/plain");
resp.getWriter().write("The email address of " + userToRetrieve + " is " + user.getEmailAddress());
}