SQL to Java Code Generator

Hi,
while generating the sql2java-classes for a oracle db, I got some datatype mappings which seems strange to me, f.e. the java-type java.lang.Object is generated for the db-type NVARCHAR2 which should be mapped into a java.lang.String.
I'd like to configure the following mappings:

NUMBER(10,0) --> Long
NVARCHAR2 --> String

Where and how can I change the dataype mappings?
(I found the 3 examples for the DATE, TIME and TIMESTAMP mappings in the sql2java.properties, but can other types be mapped there too? How?)

By the way: I found, that the generation results in other datatype mappings if I choose a MySQL DB ...

greetings
thomas