code: public List<AlternateEmail> addAlternateEmail(long userId, List<AlternateEmail> altEmails) throws SmartsheetException {
          Util.throwIfNull(altEmails);
          if (altEmails.size() == 0) {
              return altEmails;
          }
          return this.postAndReceiveList("users/" + userId + "/alternateemails", altEmails, AlternateEmail.class);
      }
docs: Add an alternate email.
  
  It mirrors to the following Smartsheet REST API method: POST /users/{userId}/alternateemails
  
  @param userId the id of the user
  @param altEmails AlternateEmail alternate email address to add.
  @return the resource (note that if there is no such resource, this method will throw
  ResourceNotFoundException rather than returning null).
  @throws IllegalArgumentException if any argument is null or empty string
  @throws InvalidRequestException if there is any problem with the REST API request
  @throws AuthorizationException if there is any problem with  the REST API authorization (access token)
  @throws ResourceNotFoundException if the resource cannot be found
  @throws ServiceUnavailableException if the REST API service is not available (possibly due to rate limiting)
  @throws SmartsheetException if there is any other error during the operation