code: public List<String> getGroupNameAttributes() throws GuacamoleException {
          return environment.getProperty(
              LDAPGuacamoleProperties.LDAP_GROUP_NAME_ATTRIBUTE,
              Collections.singletonList("cn")
          );
      }
docs: Returns all attributes which should be used to determine the unique
  identifier of each user group. By default, this will be "cn".
  
  @return
  The attributes which should be used to determine the unique
  identifier of each group.
  
  @throws GuacamoleException
  If guacamole.properties cannot be parsed.