public GrantedOAuth2AccessToken build() {
        return new GrantedOAuth2AccessToken(accessToken, tokenType,
                                            (issuedAt == null) ? Instant.now() : issuedAt, expiresIn,
                                            refreshToken, scope.build(), extras.build(), rawResponse);
    }
Builds a new instance of {@link GrantedOAuth2AccessToken} based on the configured parameters.
oauth2/src/main/java/com/linecorp/armeria/common/auth/oauth2/GrantedOAuth2AccessTokenBuilder.java