I haven't quite tested your version, but I've been experimenting around a bit, and MaxDB does not support "call current_schema". "SELECT CURRENT_SCHEMA FROM DUAL" should do the trick, like:
Marc@Overrideprotected String getConnectionSchemaName() {DatabaseConnection connection = getConnection();if (connection == null) {return null;}try {ResultSet resultSet = ((JdbcConnection) connection).prepareCall("SELECT CURRENT_SCHEMA FROM DUAL").executeQuery();resultSet.next();return resultSet.getString(1);} catch (Exception e) {LogFactory.getLogger().info("Error getting default schema", e);}return null;}