Usage of "line_total" for coupons in WC_Gateway_PPEC_Client::_get_rounded_total_in_order() seems unnecessary

[jorgeatorres]

In #677, we introduced the following code as part of changes dealing with amount mismatch and discounts (see #485 for details):

woocommerce-gateway-paypal-express-checkout/includes/class-wc-gateway-ppec-client.php

Lines 868 to 872 in ed4161e

	if ( 'coupon' === $values['type'] ) {
	$amount = round( $values['line_total'], $decimals );
	$rounded_total -= $amount;
	continue;
	}

While testing compatibility with PHP 8 I noticed that direct access to WC_Order_Item_Coupon is now deprecated, which results in deprecation warnings being logged:

[19-Nov-2020 16:28:26 UTC] The WC_Order_Item_Coupon::offsetGet function is deprecated since version 4.4.0.

I wanted to remove those warnings but then I realized this code doesn't seem to be doing much right now as "line_total" is not even set for coupon order items (i.e. it is null). As this doesn't seem to have an impact (and discounts/totals look fine on PayPal's side) It'd be good to confirm whether we even need this code anymore.

[BrianHenryIE]

FYI, we're getting those deprecation warnings on PHP 7.3.24 with WP_DEBUG enabled.