@Override
    public Collection<ActiveConnectionRecord> getActiveConnections(Connection connection) {
        return activeConnections.get(connection.getIdentifier());
    }
Returns a list of all balanced connections within a given connection
group. If the connection group is not balancing, or it contains no
connections, an empty list is returned.

@param user
    The user on whose behalf the balanced connections within the given
    connection group are being retrieved.

@param connectionGroup
    The connection group to retrieve the balanced connections of.

@return
    A list containing all balanced connections within the given group,
    or an empty list if there are no such connections.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/tunnel/AbstractGuacamoleTunnelService.java