Iam trying to intergate One Drive With my Application

Question

In the Code Flow stage cannot able to Redeem the code for access tokens getting 401 error my code

@RequestMapping("/oauth2/callback/microsoft")
	    public ResponseEntity<Response> callbackUrl(
	            HttpServletRequest request,
	            HttpSession httpSession) {
	        String code = request.getParameter("code");
	        String tokenEndpoint = "https://login.microsoftonline.com/common/oauth2/v2.0/token";
	        String clientId = "";
	        String redirectUri = "http://localhost:8080/oauth2/callback/microsoft";
	        String clientSecret = "";
	       
	        String grantType = "authorization_code";

	        try {
	            URL url = new URL(tokenEndpoint);
	            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

	            // Set the request method to POST
	            conn.setRequestMethod("POST");
	            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
	            conn.setDoOutput(true);

	            // Create the request body
	            String requestBody = "client_id=" + clientId +
	                    "&redirect_uri=" + redirectUri +
	                    "&client_secret=" + clientSecret +
	                    "&code=" + code +
	                    "&grant_type=" + grantType;

	            // Write the request body to the connection
	            try (OutputStream os = conn.getOutputStream()) {
	                byte[] input = requestBody.getBytes("utf-8");
	                os.write(input, 0, input.length);
	            }

	            // Get the response
	            int responseCode = conn.getResponseCode();
	            
	            Response response3 = new Response(201, "error:"+responseCode);
	            
	            if (responseCode == 200) {
	                Scanner scanner = new Scanner(conn.getInputStream());
	                String responseBody = scanner.useDelimiter("\\A").next();
	                System.out.println("Access Token Response: " + responseBody);
	                scanner.close();
	                conn.disconnect();
	             // Return a success message or data as needed
	                
	            } else {
	            	Scanner scanner = new Scanner(conn.getInputStream());
		                String responseBody = scanner.useDelimiter("\\A").next();
		                System.out.println("Access Token Response: " + responseBody);
		                scanner.close();
		                conn.disconnect();
	               
	            }
	            return new ResponseEntity<Response>(response3, HttpStatus.OK);	        
	            
	        } catch (Exception e) {
	            e.printStackTrace();
	            Response response3 = new Response(201, "error:"+e);
	            return new ResponseEntity<Response>(response3, HttpStatus.OK);	        
	        }
	        
	        
	        
	       
	    }