how to get Person id and assignment id from termination business event

We have a subscription based on business event oracle.apps.per.api.ex_employee.actual_termination_emp, which calls a package.

Within the function we have the following code, but the values for person id and assignment id are blank

FUNCTION xx_process (p_subscription_guid IN RAW, p_event IN OUT wf_event_t)

   RETURN VARCHAR2

  IS   l_param_list  wf_parameter_list_t;

   l_param_name  VARCHAR2 (240);

   l_param_value  VARCHAR2 (2000);

   l_event_name  VARCHAR2 (2000);

   l_event_key   VARCHAR2 (2000);

 l_event_data  VARCHAR2 (4000);

 l_person_id NUMBER;

 l_assignment_id NUMBER;

  BEGIN

   l_param_list := p_event.getparameterlist;