Error log shows id / order_key was called incorrectly

I had a query with regards a custom payment gateway that I have added.

Now the gateway works fine without issues and am able to do transactions. But when I see the error log file there is an error being generated as follows

id was called incorrectly. Order properties should not be accessed directly. Backtrace: ..., wc_doing_it_wrong. This message was added in version 3.0.
order_key was called incorrectly. Order properties should not be accessed directly. Backtrace: ..., wc_doing_it_wrong. This message was added in version 3.0.

The error seems to be generated when we redirect post return from gateway
'redirect' => add_query_arg( 'order', $order->id, add_query_arg( 'key', $order->order_key,

I read at a couple of places some suggest that

$order->id should be changed to $order->get_id()
and $order->order_key should be changed to $order->get_order_key()

So can someone confirm thats correct because I dont want to disturb the live gateway.
Thanks