Twitter streaming API - Error 401 Unauthorized - api

Question

Running a java main program to call twitter streaming api. I have generated a bearer token and passing to the api. But getting the error response Error 401 Unauthorized
Is passing the bearer token right way to authenticate? If not what is the right way to do this?
SSLConnectionSocketFactory sslsf = getSSLConnectionFactory();
CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(sslsf).build();
try {
HttpHost target = new HttpHost("stream.twitter.com", 443, "https");
new BasicHttpContext();
HttpPost httpPost = new HttpPost("/1.1/statuses/filter.json");
StringEntity postEntity = new StringEntity("track=birthday","UTF-8");
postEntity.setContentType("application/x-www-form-urlencoded");
httpPost.setEntity(postEntity);
//httpPost.setHeader("Authorization", "Bearer " + Base64.encodeBase64(bearerToken.getBytes()));
httpPost.setHeader("Authorization", "Bearer " + bearerToken);
httpPost.setHeader("User-Agent", "Your Program Name");
httpPost.setHeader("Host", "stream.twitter.com");
HttpResponse response = httpClient.execute(target, httpPost,new BasicHttpContext());
BufferedReader reader = new BufferedReader(new InputStreamReader(
response.getEntity().getContent()));
String line = null;
StringBuffer buffer = new StringBuffer();
while ((line = reader.readLine()) != null) {
buffer.append(line);
if(buffer.length()>30000) break;
}
System.out.println(buffer);
//return new EventImpl(buffer.toString().getBytes());
} catch (Exception e) {
e.printStackTrace();
}