Correctly handle the case when PayPal returns token expires_in field as a string
Correctly handle the case when PayPal returns token expires_in field as a string

Credit goes to oauth2 package.
https://github.com/golang/oauth2/blob/master/internal/token.go#L62

logpacker/paypalsdk,logpacker/paypalsdk,logpacker/PayPal-Go-SDK