code: private User resolveUser(RequestContext requestContext, User[] users) {
      User resolvedUser = null;
      for (User user : users) {
        if (user != null && resolvedUser != null && !user.getId().equals(resolvedUser.getId())) {
          Messages messages = Messages.getInstance();
          Locale locale = requestContext.getRequest().getLocale();
          throw new SmvcRuntimeException(EdelfoiStatusCode.LOGIN_MULTIPLE_ACCOUNTS, messages.getText(locale, "exception.1023.loginMultipleAccounts"));
        }
        else {
          resolvedUser = user == null ? resolvedUser : user;
        }
      }
      return resolvedUser;
    }
docs: Determines a common <code>User</code> corresponding to the given array of users. If all users are <code>null</code>, returns <code>null</code>.
  If the users do not share the same identifier, an <code>SmvcRuntimeException</code> is thrown.
  
  @param requestContext Request context
  @param users The list of users to validate
  
  @return The common <code>User</code> corresponding to the given array of users, or <code>null</code> if all given users are <code>null</code>
  
  @throws SmvcRuntimeException If all given users do not share the same identifier