public class BearerTokens(
    public val accessToken: String,
    public val refreshToken: String?
)

fun getTokens(): BearerTokens? {
	val accessToken = ...
	val refreshToken = ...
	return if (accessToken != null && refreshToken != null) {
		BearerTokens(accessToken, refreshToken)
	} else {
		null
	}
}

fun getRefreshToken(): Pair<String, String> {
	val bearerTokens = getTokens()


	// version 1: 
	// Expected: Pair<String, String>, got Pair<String, String?>
	/*
	if (bearerTokens?.refreshToken != null) {
		return "Bearer" to bearerTokens.refreshToken
	}
	*/

	// version 2:
	// Expected: Pair<String, String>, got Pair<String, String?>
	/*
	bearerTokens?.refreshToken?.let {
		return "Bearer" to bearerTokens.refreshToken
	}
	*/

	// version 3: works
	/*
	bearerTokens?.refreshToken?.let { refreshToken ->
		return "Bearer" to refreshToken
	}
	*/

	// if no token, return basic auth
	return getBasicAuthorization()
}