public Set<String> getConnectionGroupIdentifiers() {
        return connectionGroupIdentifiers;
    }
Returns the identifiers of all readable child connection groups within
this connection group. This is set only when the parent connection group
is queried, and has no effect when a connection group is inserted,
updated, or deleted.

@return
    The identifiers of all readable child connection groups within this
    connection group.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/connectiongroup/ConnectionGroupModel.java