public JiraUser getUser(string userId)
 {
     lock (this) {
         if (userId == null)
         {
             return(NullUser);
         }
         if (!users.ContainsKey(userId))
         {
             users[userId] = new JiraUser(userId, null);
         }
         return(users[userId]);
     }
 }
 public void putUser(JiraUser user)
 {
     lock (this) {
         users[user.Id] = user;
     }
 }