protected Attribute getUsers(
      long ldapServerId,
      long companyId,
      LdapContext ldapContext,
      Attributes attributes,
      UserGroup userGroup,
      Properties groupMappings)
      throws Exception {

    Attribute attribute = attributes.get(groupMappings.getProperty("user"));

    if (attribute == null) {
      return null;
    }

    String postfix = LDAPSettingsUtil.getPropertyPostfix(ldapServerId);

    String baseDN = PrefsPropsUtil.getString(companyId, PropsKeys.LDAP_BASE_DN + postfix);

    StringBundler sb = new StringBundler(7);

    sb.append("(&");
    sb.append(
        PrefsPropsUtil.getString(companyId, PropsKeys.LDAP_IMPORT_GROUP_SEARCH_FILTER + postfix));
    sb.append("(");
    sb.append(groupMappings.getProperty("groupName"));
    sb.append("=");
    sb.append(escapeValue(userGroup.getName()));
    sb.append("))");

    return PortalLDAPUtil.getMultivaluedAttribute(
        companyId, ldapContext, baseDN, sb.toString(), attribute);
  }