idoklad-itam-name-with-sku.php

<?php 
//Add sku code into item name for invoice
add_filter( 'idoklad_order_item_name', 'custom_idoklad_item_name', 10, 2 );
function custom_idoklad_item_name( $name, $data ){
  $_product = wc_get_product( $data['variation_id'] ? $data['variation_id'] : $data['product_id'] );
  $sku = $_product->get_sku();
  if( !empty( $sku ) ){
    $name = $name . ' ' . $sku;
  }
  
  return $name;
  
}