How to get access token the non-legacy way ?

[mhcwebdesign]

For a given code and application_id and application_secret how exactly do I get the access token using the new non-legacy API ?

Google AI claims this, which I think is wrong:

You cannot use an
OAuthClient class in the current (non-legacy) Square PHP SDK because that class was part of the retired, legacy connect-php-sdk package. The correct, non-legacy class to use is OAuthApi, which is accessed via the main SquareClient instance.

?