HistoricDecisionInstanceAuthorizationTest#testQueryWithReadPermissionOnDecisionDefinition fails using IBM Informix DB

Running latest master version extended by my IBM Informix support fails at HistoricDecisionInstanceAuthorizationTest#testQueryWithReadPermissionOnDecisionDefinition().
Only this single test within this class fails, all other tests run successful, including
#testQueryWithReadPermissionOnAnyDecisionDefinition().
Nailed down the cause to the inner join in selectHistoricDecisionInstancesByQueryCriteriaSql, precise the nested select.
At this location the nesting should not be necessary for any database.
Removing it solved my failure (PR will follow).
Tested also against H2 and Oracle 12 databases successfully.