LOV Component in WEBADI Does not validate

Dear All,

      I have created a Web ADI Integrator, Layout and thereafter created LOV component using the below mentioned API. This works fine and the list is getting populated accordingly for attribute1. Here the issue is the webadi sheet allows user to enter freetext value as well; Wherein user can always ignore the list and can enter some value. I would like to enable validate from list option for this column appreciate if you could provide any input on this. Thanks in advance.

1. DECLARE
2.    ln_application_id    NUMBER;
3.    lc_integtr_code      VARCHAR2 (50);
4.    lx_interface_code    VARCHAR2 (50);
5.    lx_param_list_code   VARCHAR2 (50);