JDBCR4 help: having trouble front-ending Java DatabaseMetaData.getIndexInfo() for ILE RPG

With nobody answering on the RPG list . . .

I'm having difficulty adding an RPG front-end for the DatabaseMetaData.getIndexInfo() method to JDBCR4.

Given that the following Java fragment:

DatabaseMetaData dbmd = conn.getMetaData();
ResultSet indexInfo = dbmd.getIndexInfo(null, "AQUESTVIEW", "VIEWCUS",
true, true);
while(indexInfo.next()){
System.out.println(" " + indexInfo.getString(5)
+ " " + indexInfo.getString(6)
+ " " + indexInfo.getShort(7)
+ " " + indexInfo.getShort(8)
+ " " + indexInfo.getString(9)
+ " " + indexInfo.getString(10));
}

produces the expected output of:

AQUESTVIEW VIEWCUS 3 1 CUNMBR A
null null 0 0 null null

can anybody suggest a reason (other than my own inexperience with front-ending Java for RPG) why the following blows up when executed:

(in JDBCR4):

D getIndexInfo...
D PR ExtProc(*JAVA:
D 'java.sql.DatabaseMetaData':
D 'getIndexInfo')
D like(ResultSet)
D catalog like(jString) const
D schema like(jString) const
D table like(jString) const
D unique 1N value
D approximate 1N value

. . .

P JDBC_GetIndexInfo...
P B export
D JDBC_GetIndexInfo...
D PI like(ResultSet)
D dbmd like(DatabaseMetaData) const
D catalog 32767A varying const options(*varsize)
D schema 32767A varying const options(*varsize)
D table 32767A varying const options(*varsize)
D unique 1N
D approximate 1N
D temp s like(ResultSet)
D rs s like(ResultSet)
D cat s like(jString)
D sch s like(jString)
/free
jdbc_begin_object_group(50);
if (catalog = '*NULL');
cat = *NULL;
else;
cat = s(catalog);
endif;
if (schema = '*NULL');
sch = *NULL;
else;
sch = s(schema);
endif;
monitor;
temp = getIndexInfo(dbmd: cat: sch: s(table):
unique: approximate);
jdbc_end_object_group(temp: rs);
on-error;
jdbc_end_object_group();
return *NULL;
endmon;

return rs;
/end-free
P E

and in the calling program:

rs = JDBC_GetIndexInfo(dbmd: '*NULL': %TRIM(MPLIBR): %TRIM(MPFILE):
*ON: *ON);
jdbc_freeResult(rs);

(Note that, as with my front-end for DatabaseMetaData.getPrimaryKeys(), there is code in the front-end to turn the quoted string '*NULL' into an actual *NULL passed to the Java method.)

It blows up at the freeResult call. In my own miniscule experience with expanding JDBCR4, this usually happens if the result set passed is null. That suggests that I've screwed up something in the call to getIndexInfo, such that it's returning *NULL instead of a result set.

But what?

--
JHHL