"Includes" in Convertdefs.php

I am trying to include a JavaScript in convertdefs.php(ConvertLead Layout). When i include external JS in other files as shown below inside templateMeta array, it is working fine but when i include file like this in

convertdef.php

under Oppertunity instance, it does not include JS. Can anyone suggest me where am i lagging.

General Info:- I am using SuiteCRM 7.7.9.

// Code to include External JS

'includes' =>
        array (
            0 =>
                array (
                    'file' => 'custom/include/javascript/buyorsell_opp.js',
                ),
        ),

// Code to call JS on a field

'displayParams' =>
              array(
                  'field' =>
                      array(
                          'onChange' => 'display()',
                      ),
              ),