Estoy desarrollando una pequeña aplicación web en la que me estoy integrando con las API de dominio de Google+. Estoy usando la autenticación OAuth2. He generado client_id y client_secret para mi aplicación web desde la consola de Google API. Usando las API de Google+ Domain, puedo generar el token de acceso.

Generando URL de autorización

List<String> SCOPE = Arrays.asList(
"https://www.googleapis.com/auth/plus.me",
"https://www.googleapis.com/auth/plus.circles.read",
"https://www.googleapis.com/auth/plus.stream.write");

//Sets up Authorization COde flow
GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(new NetHttpTransport(),
    new JacksonFactory(),
    "xxx","yyy",SCOPE).setApprovalPrompt("force").setAccessType("offline").build();

//Builds the uthorization URL
String url = flow.newAuthorizationUrl().setRedirectUri(<REDIRECT_URI>).build();
out.println("<div id='googleplus'></div><a href='"+url+"' rel='external' ><img src='googleplus.jpg'></a> <b>Configure</b></div>");
session.setAttribute("CodeFlow", flow);

Despues de la autorizacion

 GoogleAuthorizationCodeFlow flow=(GoogleAuthorizationCodeFlow)session.  getAttribute("CodeFlow");

//After authorization,fetches the value of code parameter
String authorizationCode=request.getParameter("code");

//Exchanges the authorization code to get the access token
GoogleTokenResponse tokenResponse=flow.newTokenRequest(authorizationCode).
    setRedirectUri(<REDIRECT_URI>).execute();

GoogleCredential credential = new GoogleCredential.Builder().setTransport(new  NetHttpTransport()).setJsonFactory(new JacksonFactory())
.setClientSecrets("xxx", "yyy")
.addRefreshListener(new CredentialRefreshListener(){

    public void onTokenErrorResponse(Credential credential, TokenErrorResponse errorResponse) throws java.io.IOException{
        System.out.println("Credential was not refreshed successfully. "
                + "Redirect to error page or login screen.");

    }


    @Override
    public void onTokenResponse(Credential credential, TokenResponse tokenResponse)
            throws IOException {
        System.out.println("Credential was refreshed successfully.");
         System.out.println("Refresh Token :"+tokenResponse.getRefreshToken());

    }
}).build();

//Set authorized credentials.
credential.setFromTokenResponse(tokenResponse);
credential.refreshToken();

Obteniendo información del círculo:

PlusDomains plusDomains = new PlusDomains.Builder(
        new NetHttpTransport(), new JacksonFactory(), credential)
        .setApplicationName("DomainWebApp")
        .setRootUrl("https://www.googleapis.com/")
        .build();
PlusDomains.Circles.List listCircles=plusDomains.circles().list("me");
listCircles.setMaxResults(5L);
System.out.println("Circle URL:"+listCircles.buildHttpRequestUrl());
CircleFeed circleFeed=listCircles.execute();
System.out.println("Circle feed:"+circleFeed);
List<Circle> circles =circleFeed.getItems();

while (circles != null) {
      for (Circle circle : circles) {
          out.println("Circle name : "+circle.getDisplayName()+" Circle id : "+circle.getId());
      }

      // When the next page token is null, there are no additional pages of
      // results. If this is the case, break.
      if (circleFeed.getNextPageToken() != null) {
        // Prepare the next page of results
        listCircles.setPageToken(circleFeed.getNextPageToken());

        // Execute and process the next page request
        circleFeed = listCircles.execute();
        circles = circleFeed.getItems();
      } else {
        circles = null;
      }
    }

Me sale el siguiente error:

com.google.api.client.googleapis.json.GoogleJsonResponseException: 403 Forbidden
{
  "code" : 403,
  "errors" : [ {
    "domain" : "global",
    "message" : "Forbidden",
    "reason" : "forbidden"
  } ],
  "message" : "Forbidden"
}
    com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:145)
    com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:113)

Nota: También he habilitado la API de dominio de Google+ en mi consola de la API de Google.REDIRECT_URI ="http://localhost:8080/DomainWebApp/oauth2callback" ya que es una aplicación web. ¿Alguna sugerencia?