Error while creating a pushtopic from java

I am trying to create a push topic in java by following this link . Since there were changes in the eclipse httpclient library (I am using version 9.2.5) I had to make corresponding changes and the code now looks as below. While making the http post request for creating the push request I get the response as "HttpResponse[HTTP/1.1 400 Bad Request]@66fa8363"

private static final String API_VERSION = "23.0";

    public static void main(String[] args) throws Exception {
        if (args.length < 2) {
            System.err.println("Usage: MakeTopic topicname query");
            System.exit(-1);
        }

        String topicname = args[0];
        String query = args[1];

        HttpClient httpClient = new HttpClient(new HttpClientTransportOverHTTP(), new SslContextFactory(true));
        httpClient.start();

        JSONObject authResponse = oauthLogin(httpClient);
        System.out.println("Login response: " + authResponse.toString(2));
        if (!authResponse.has("access_token")) {
            throw new Exception("OAuth failed: " + authResponse.toString());
        }

        String url = authResponse.getString("instance_url")
                + "/services/data/v23.0/sobjects/PushTopic/";

        JSONObject topic = new JSONObject();

        topic.put("ApiVersion", API_VERSION);
        topic.put("Name", topicname);
        topic.put("Query", query);

        System.out.print("PushTopic data: ");
        System.out.println(topic.toString(2));

        System.out.println("Push URL : " + url);
        System.out.println("Topic : " + topic.toString());
        httpClient.POST(url).header(HttpHeader.CONTENT_TYPE, "application/json")
                .header(HttpHeader.AUTHORIZATION, "OAuth " + authResponse.getString("access_token"))
                .content(new StringContentProvider(topic.toString())).send(new Response.CompleteListener() {
            @Override
            public void onComplete(Result result) {
                System.out.println("Result status : " + result.isSucceeded());
                System.out.printf("Response : " + result.getResponse()); //                System.out.println(result.getResponse().getReason()); //               result.getFailure().printStackTrace();
            }
        });

        while (true) {
            TimeUnit.MINUTES.sleep(5);
        }
    }

    private static JSONObject oauthLogin(HttpClient httpClient) throws Exception {
        String url = LOGIN_SERVER + "/services/oauth2/token";
        String message = "grant_type=password&client_id=" + CLIENT_ID
                + "&client_secret=" + CLIENT_SECRET + "&username=" + USERNAME
                + "&password=" + PASSWORD;


        ContentResponse contentResponse = httpClient.POST(url).header(HttpHeader.CONTENT_TYPE, "application/x-www-form-urlencoded")
                .content(new StringContentProvider(message)).send();

        return new JSONObject(new JSONTokener(contentResponse.getContentAsString()));
    }

The command output of the above execution is

2014-11-28 11:42:45.579:INFO::main: Logging initialized @70ms
Login response: {
  "id": "https://login.salesforce.com/id/00D90000000mOWsEAM/00590000001XDqBAAW",
  "issued_at": "1417155166607",
  "instance_url": "https://ap1.salesforce.com",
  "token_type": "Bearer",
  "access_token": "00D90000000mOWs!AQkAQDtcskg4wEH5yMMOPnG1TWLx9ENr8zaa9xc.wyoq8pCDKuMgYjQD9Hy_d3kep8EssxPTRsDssS.0a7K2GTxq9NCuV6eE",
  "signature": "Nlut7j39pc8rsvFjAVVoQIHU6f7oUkbe9YKlFbyYt6s="
}
PushTopic data: {
  "Name": "TestTableTopic",
  "Query": "SELECT Id, Id__c FROM TestTable__c",
  "ApiVersion": "23.0"
}
Push URL : https://ap1.salesforce.com/services/data/v23.0/sobjects/PushTopic/
Topic : {"Name":"TestTableTopic","Query":"SELECT Id, Id__c FROM TestTable__c","ApiVersion":"23.0"}
Result status : true
Response : HttpResponse[HTTP/1.1 400 Bad Request]@66fa8363

Unfortunately I can't find a way to print out more details on http response. What could be going wrong?