"create type" custom types not supported by JDBC

I'm getting errors when I'm trying to access my custom data types
through JDBC.

If I don't supply a custom map using Connection.setTypeMap() then I'm
getting ...

org.postgresql.util.PGobject cannot be cast to Money at ...
Money m = (Money) resultSet.getObject(1); // Money is my class to
handle multi-currency money types

If I add a mapping with ...
map.put("couk_cleverthinking_gwappo_currency",Class.forName("Money") )
connection.setTypeMap(map)

Then I get ...
java.lang.ClassCastException: java.lang.Class cannot be cast to
java.sql.SQLData
at
org.postgresql.jdbc2.AbstractJdbc2Connection.getObject(AbstractJdbc2Connection.java:403)

Poking around the source code of AbstractJdbc2Connection it looks like
this functionality isn't support.

Please could somebody confirm this is the cause and offer any insights
as to when it might be included.

Perhaps an "Unsupported feature" error would be more helpful than a
ClassCastException.

Very best wishes
Roy