How to modify the SQLParser to handle NULL in column definitions ?

[Duncan Groenewald]

Can anyone provide a pointer as to what needs to be modified in order 
for derby to handle a column definition that includes a NULL, as shown 
below:

create testtable(
   code int   NOT NULL,
   description varchar(32) NULL
)
I have no real idea how the parser works but figured it can't be that 
hard to be able to handle this without complaining about a syntax 
error.  It looks to me like this gets done in the SQLParser.java file 
but I have not been able to figure out how it works.  There is also a 
sqlgrammar.jj file which I assume is not actually used for anything 
although it looks like it might be some kind of definition file for 
SQLParser.

Thanks in advance.
Duncan