public static function get_refund_request( $order, $amount = null, $reason = '' ) {
		$request = array(
			'VERSION'       => '84.0',
			'SIGNATURE'     => self::$api_signature,
			'USER'          => self::$api_username,
			'PWD'           => self::$api_password,
			'METHOD'        => 'RefundTransaction',
			'TRANSACTIONID' => $order->get_transaction_id(),
			'NOTE'          => html_entity_decode( wc_trim_string( $reason, 255 ), ENT_NOQUOTES, 'UTF-8' ),
			'REFUNDTYPE'    => 'Full',
		);
		if ( ! is_null( $amount ) ) {
			$request['AMT']          = number_format( $amount, 2, '.', '' );
			$request['CURRENCYCODE'] = $order->get_currency();
			$request['REFUNDTYPE']   = 'Partial';
		}
		return apply_filters( 'woocommerce_paypal_refund_request', $request, $order, $amount, $reason );
	}