How to retrieve temporary BLOB value from PLSQL to Java?

[Corrine]

I am trying to pass a temporary BLOB that I've created in Java, to a
PLSQL function that modifies it, and then to retrieve this modified
value back to Java, all using JDBC.

I can't figure out how to get the modified BLOB object back to Java
after the PLSQL block has finished executing.

I do:

BLOB bl = BLOB.createTemp orary(db,true,B LOB.DURATION_SE SSION);
CallableStateme nt plsqlblock = conn.prepareCal l(
"declare\n" +
" stuff... \n"+
"begin\n"+
" procThatModifie sBLOB(?);\n"+
"end;\n");
plsqlblock.setB lob(1, bl);
plsqlblock.exec ute();

bl = plsqlblock.getB lob(1); //**** doesn't work.

How do I retrieve the modified value of "bl" after "plsqlblock "
finishes executing?