public GrantedOAuth2AccessTokenBuilder refreshToken(String refreshToken) {
        this.refreshToken = requireNonNull(refreshToken, "refreshToken");
        return this;
    }
{@value OAuth2Constants#REFRESH_TOKEN} Access Token response field,
OPTIONAL. The refresh token, which can be used to obtain new access tokens using the same
authorization grant as described at
<a href="https://datatracker.ietf.org/doc/html/rfc6749#section-6">[RFC6749], Section 6</a>.
oauth2/src/main/java/com/linecorp/armeria/common/auth/oauth2/GrantedOAuth2AccessTokenBuilder.java