使用Java从Google请求OAUTH的JWT签名无效

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.oauth2.Oauth2;
import com.google.api.services.oauth2.model.Userinfo;

import java.io.File;
import java.io.IOException;

public class GoogleOauthExample {
    private static final String CLIENT_SECRET_FILE = "/path/to/client_secret.json";
    private static final List<String> SCOPES = Arrays.asList(Oauth2Scopes.USERINFO_EMAIL);
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKENS_DIRECTORY_PATH = "tokens";

    public static void main(String[] args) throws IOException {
        final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
        GoogleCredential credential = GoogleCredential.fromStream(new FileInputStream(new File(CLIENT_SECRET_FILE)))
                .createScoped(SCOPES);

        Oauth2 oauth2 = new Oauth2.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential)
                .setApplicationName("Your Application Name")
                .build();

        Userinfo userInfo = oauth2.userinfo().get().execute();
        System.out.println(userInfo.getEmail());
    }
}