We recently updated from version 4.3.1 to 5.4.1 and noticed that the order-by attribute on maps defined via old hbm.xml files stopped working.
The problem seems to be that the PluralAttributeSourceMapImpl class does not implement the Orderable interface. After implementing this interface the generated sql string contains the defined order by.

I have attached my PluralAttributeSourceMapImpl.java which implements Orderable and fixes the problem for me.