OSS driver 109 (and SIMBA 273) both return an empty Resultset from DatabaseMetadata.getFunctions.

   int ctr = 0;
            ResultSet functions = dbConnection.getMetaData().getFunctions("catalognamehere", "schemanamehere", "%");
            while (functions.next()) {
                  System.out.println(functions.getString(3));
                  ++ctr;
            }

            System.out.println("Functions found " + ctr)    ;

create or create or replace function catalogname.schemaname.FNOPARAMS ()
returns smallint
language sql deterministic contains sql
return 1;

create or replace functioncatalogname.schemaname.FINSINT ( PSINT smallint )
returns smallint
language sql deterministic contains sql
return PSINT;

....