WooCommerce API customizations

This code snippet will add a metadata field to the order json object returned by the WooCommerce API

add_filter('woocommerce_rest_prepare_shop_order_object', 'filter_order_response', 10, 3);
function filter_order_response($response, $post, $request){
 $order_data = $response->get_data();

 foreach ( $order_data['line_items'] as $key => $item ) {
    $order_data['line_items'][ $key ]['your_meta_data_key'] = get_post_meta( $item['product_id'], 'your_meta_data_key', true );
 }

 $response->data = $order_data;
 return $response;
}