Working wtih nested Java object in PL/SQL

I am writing a pl/sql procedure that will accept a nested Java object parse it and eventually bulk load the data to Oracle.  As part of the object I need to update data in the nested portion of the object, and have run into some issues getting it to work.  Any advice in what I am doing wrong would be helpfull.  Code attached:

create or replace type EVENT_DATA_ARRAY as object
   (EVENT_ID_FK NUMBER, 
    ELEMENT_NAME VARCHAR2(250),
    ELEMENT_VALUE VARCHAR2(4000)
   );

create or replace type EVENT_DATA_TAB as table of EVENT_DATA_ARRAY;

create or replace type EVENT_OBJECT as object