code: public UsersResponse listGroupUsers(String accountId, String groupId) throws ApiException {
      return listGroupUsers(accountId, groupId, null);
    }
docs: Gets a list of users in a group.
  Retrieves a list of users in a group.
  @param accountId The external account number (int) or account ID Guid. (required)
  @param groupId The ID of the group being accessed. (required)
  @return UsersResponse