code: private Auth constructAuth(String authToken, String tokenSecret, String username) throws IOException {
  
          Auth auth = new Auth();
          auth.setToken(authToken);
          auth.setTokenSecret(tokenSecret);
  
          // Prompt to ask what permission is needed: read, update or delete.
          auth.setPermission(Permission.fromString("delete"));
  
          User user = new User();
          // Later change the following 3. Either ask user to pass on command line or read
          // from saved file.
          user.setId(nsid);
          user.setUsername((username));
          user.setRealName("");
          auth.setUser(user);
          this.authStore.store(auth);
          return auth;
      }
docs: If the Authtoken was already created in a separate program but not saved to file.
  
  @param authToken
  @param tokenSecret
  @param username
  @return
  @throws IOException