code: public List<String> getAttributes() throws GuacamoleException {
          return environment.getProperty(
              LDAPGuacamoleProperties.LDAP_USER_ATTRIBUTES,
              Collections.<String>emptyList()
          );
      }
docs: Returns names for custom LDAP user attributes.
  
  @return
  Custom LDAP user attributes as configured in guacamole.properties.
  
  @throws GuacamoleException
  If guacamole.properties cannot be parsed.