refresh token is null using Spring Security OAuth2

I am trying to integrate Google OAuth 2 using Spring Security. Everything works well, but refresh_token is null.

Here is my config:

@Bean
public OAuth2ProtectedResourceDetails googleOAuth2Details() {
    AuthorizationCodeResourceDetails googleOAuth2Details = new AuthorizationCodeResourceDetails();
    googleOAuth2Details.setAuthenticationScheme(form);
    googleOAuth2Details.setClientAuthenticationScheme(form);
    googleOAuth2Details.setClientId(googleClientId);
    googleOAuth2Details.setClientSecret(googleClientSecret);
    googleOAuth2Details.setUserAuthorizationUri(googleOAuthUri);
    googleOAuth2Details.setAccessTokenUri(googleTokenUrl);
    googleOAuth2Details.setScope(asList("openid","email"));
    return googleOAuth2Details;
}

I read that in order to get refresh_token, access_type has to be "offline". But what is the way to set it in Spring?