Spring Security: How to get details from the principal?

Using spring boot and spring security, the details of user are available in principal object. But it has only few methods to retrieve details, like getName().

How do I get other details out of it?

Currently my class looks like this

@SpringBootApplication
@RestController
public class DemoOAuth2Application {

    @RequestMapping("/user")
    public Principal user(Principal principal) {
        return principal;
    }


    public static void main(String[] args) {
        SpringApplication.run(DemoOAuth2Application.class, args);
    }
}

It returns this,

{
  "authorities": [
    {
      "authority": "ROLE_USER"
    }
  ],
  "details": {
    "remoteAddress": "0:0:0:0:0:0:0:1",
    "sessionId": "43Fxxxxxx",
    "tokenValue": "ya29.xxxxxxxxx",
    "tokenType": "Bearer",
    "decodedDetails": null
  },
  "authenticated": true,
  "userAuthentication": {
    "authorities": [
      {
        "authority": "ROLE_USER"
      }
    ],
    "details": {
      "id": "106xxxxx",
      "email": "xxxxxxxx@gmail.com",
      "verified_email": true,
      "name": "xxxx yyyyyy",
      "given_name": "xxxxxx",
      "family_name": "yyyyy",
      "link": "https://plus.google.com/xxxxxxxxxx",
      "picture": "https://lh5.googleusercontent.com/xxxxxx/photo.jpg",
      "locale": "en"
    },
    "authenticated": true,
    "principal": "106xxxxx",
    "credentials": "N/A",
    "name": "106xxxxxxx"
  },
  "principal": "106xxxxxxxxxxx",
  "clientOnly": false,
  "credentials": "",
  "oauth2Request": {
    "clientId": "xxxxxxxxx.apps.googleusercontent.com",
    "scope": [],
    "requestParameters": {},
    "resourceIds": [],
    "authorities": [],
    "approved": true,
    "refresh": false,
    "redirectUri": null,
    "responseTypes": [],
    "extensions": {},
    "refreshTokenRequest": null,
    "grantType": null
  },
  "name": "106xxxxxxxxxx"
}

But instead of returning all the data, I'd like to return only specific data I need. How do I get that data(specifically email, name, link, picture).