Unable to access SharePoint repository from java

Question

I'm trying to download a file from a Sharepoint repository (where I have regularly access from my corporate network) and I'm doing it from JAVA 7 program.

I'm using the following code, just got from stackoverflow, but my download attempt is failing with error : HTTP/1.1 403 Forbidden

For sake of completeness, the same request is also failing if a try from POSTMAN then it looks due something related to authentication schema. Of course I have no problem when accessing from common WEB browsers.

CredentialsProvider credsProvider = new BasicCredentialsProvider();
credsProvider.setCredentials(
    new AuthScope(AuthScope.ANY),
    new NTCredentials("username", "password", "usernamestring",    "passwordstring"));
CloseableHttpClient httpclient = HttpClients.custom()
    .setDefaultCredentialsProvider(credsProvider)
    .build();
try {
    HttpGet httpget = new HttpGet("https://xxx.sharepoint.com/sites /YYYYY/default.aspx");

System.out.println("Executing request " + httpget.getRequestLine());
CloseableHttpResponse response = httpclient.execute(httpget);
try {
          System.out.println("----------------------------------------");
        System.out.println(response.getStatusLine());
        EntityUtils.consume(response.getEntity());
    } finally {
        response.close();
    }
} finally {
    httpclient.close();
}