WooCommerce: customize "payment on site" icon

woocommerce_paymentonsite_icon.php

<?php

	/**
	 * WooCommerce Gateway Icon for "Payment On Site"
	 *
	 *
	 * @param string $icon The icon html markup
	 *
	 * @return string
	 */
function custom_woocommerce_paymentonsite_icon( $icon ) {
	$icon = 'https://pathtoimaage/paymentonsite-icon.png';
	
	return $icon;
}
add_action( 'woocommerce_paymentonsite_icon', 'custom_woocommerce_paymentonsite_icon', 1000 );