una/plugins/chargebee/ChargeBee/Models/InvoiceAppliedCredit.php

<?php

class ChargeBee_InvoiceAppliedCredit extends ChargeBee_Model
{
  protected $allowed = array('cn_id', 'applied_amount', 'applied_at', 'cn_reason_code', 'cn_date', 'cn_status');

}

?>