WooCommerce Google Analytics Pro - Ensure off-site gateways aren't tracked as referrers

sv-wc-google-analytics-pro-utm-nooverride.php

<?php // only copy this line if needed

/**
 * Add the utm_nooverride parameter to any return urls. This makes sure Google Adwords doesn't mistake the offsite gateway as the referrer.
 *
 * @link https://github.com/woothemes/woocommerce-google-analytics-integration/blob/c805bb4c24de235227c2b4b21b179d73bd8a7861/includes/class-wc-google-analytics.php#L506-L522
 *
 * @param  string $return_url WooCommerce Return URL
 * @return string URL
 */
function sv_wc_google_analytics_pro_utm_nooverride( $return_url ) {

	// remove the utm_nooverride param in case it exists
	$return_url = remove_query_arg( 'utm_nooverride', $return_url );

	// add utm_nooverride param to return URL
	$return_url = add_query_arg( 'utm_nooverride', '1', $return_url );

	return $return_url;
}
add_filter( 'woocommerce_get_return_url', 'sv_wc_google_analytics_pro_utm_nooverride' );