setObject type for Interval objects

I have an SQL SELECT which contains an expressions of the form:-

WHERE created < CURRENT_TIMESTAMP - ?

where created is a TIMESTAMP field. As a parameter I want to pass
an interval, so I used:-

PGInterval interval = new PGInterval( intervalPeriod);
stmt.setObject( 1, interval);

but Postgresql objects with:-

org.postgresql.util.PSQLException: Can't infer the SQL type to use for an
instance of org.postgresql.util.PGInterval. Use setObject() with an explicit
Types value to specify the type to use.

So I guess I need the three parameter setObject, but I do not know what
type to pass to the third parameter. I have googled, but to no avail (I
obviously asked the wrong question).

David