DuplicateNotificationsCleanupUpgradeTask sql statement fails on HSQL

java.sql.SQLException: Not in aggregate function or group by clause: org.hsqldb.Expression@1262f7c in statement [select count(*) as NOTIF_COUNT, PAGEID, SPACEID, lower(USERNAME) as USERNAME from NOTIFICATIONS group by lower(USERNAME), PAGEID, SPACEID]
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.jdbcStatement.fetchResult(Unknown Source)
at org.hsqldb.jdbc.jdbcStatement.executeQuery(Unknown Source)
at com.mchange.v2.c3p0.impl.NewProxyStatement.executeQuery(NewProxyStatement.java:34)
at com.atlassian.confluence.upgrade.DuplicateNotificationsCleanupUpgradeTask.doUpgrade(DuplicateNotificationsCleanupUpgradeTask.java:66)