availableToken

Determines the appropriate oauth token for any given query. This can be either the access token or the user token. Default behavior is to return the user token if available and fall back to the access token if not. Order of precedence:

1. User Token

2. Overridden token (In #2 because this should be used only when user is logged out. Mainly for multi-concept to use merchant specific token)

3. Merchant token (In other words, externalDeviceMerchantToken from merchant settings)

4. Client token