Error attempting delete with cascade and triggers

The scenario is a parent and child table with a cascade delete and triggers on both tables. Here are the steps to reproduce.

First, compile TestFunctions.java and put it on the classpath:

public class TestFunctions
{
public static void test(String str)
{
}
}

Next, enter commands into interactive SQL:

create table testtable (id integer, name varchar(20), primary key(id));

create table testchild (
id integer
constraint fk_id references testtable on delete cascade,
ordernum int,
primary key(id));

create procedure testproc (str varchar(20))
PARAMETER STYLE JAVA LANGUAGE JAVA EXTERNAL NAME 'TestFunctions.test';

create trigger testtabletrigger after delete on testtable referencing old as old
for each row mode db2sql call testproc(char(old.id));

create trigger testchildtrigger after delete on testchild referencing old as old
for each row mode db2sql call testproc(char(old.ordernum));

insert into testtable values (1, 'test1');

insert into testchild values (1, 10);

delete from testtable where id = 1;

The expected result is that deleting a row from "testtable" will cascade the delete to "testchild", and the triggers will be called for each delete. The actual result is that the delete is rolled back with the following error:

Error: An attempt was made to put a data value of type 'java.lang.String' into a data value of
type 'INTEGER'.
SQLState: XCL12
ErrorCode: 30000

There are no additional entries in the derby.log after the error. If only one trigger is used, or if the cascade is removed, then the delete will succeed.

This issue was found while using SymmetricDS, which uses triggers to replicate tables between Derby databases.