final OAuth20Service service = new ServiceBuilder(clientId)
                .apiSecret(clientSecret)
                .defaultScope(new ScopeBuilder("r_liteprofile", "r_emailaddress"))
                .callback("http://example.com/callback")
                .build(LinkedInApi20.instance());

    public String getAccessTokenEndpoint() {
        return "https://www.linkedin.com/oauth/**rest**/accessToken";
    }

    protected String getAuthorizationBaseUrl() {
        return "https://www.linkedin.com/oauth/**rest**/authorization";
    }

chage to

private static final String PROTECTED_RESOURCE_URL = "https://api.linkedin.com/**rest**/me";
private static final String PROTECTED_EMAIL_RESOURCE_URL
        = "https://api.linkedin.com/**rest**/emailAddress?q=members&projection=(elements*(handle~))";

..
final OAuthRequest request = new OAuthRequest(Verb.GET, PROTECTED_RESOURCE_URL);
**request.addHeader("LinkedIn-Version", "202304");**