try (CloseableHttpClient client = HttpClients.createDefault()) {
            String stringBuilder = "https://api.telegram.org/botxxxxxxx";
            String str = "{\"chat_id\":"+ss+",\"text\":\"Hi\",\"reply_markup\":{\"inline_keyboard\":[{\"text\":\"A\",\"callback_data\":\"A1\"},{\"text\":\"B\",\"callback_data\":\"C1\"}]}}";
            HttpPost httpPost = new HttpPost(stringBuilder);

            StringEntity entity = new StringEntity(str);
            httpPost.setEntity(entity);
            httpPost.setHeader("Accept", "application/json");
            httpPost.setHeader("Content-type", "application/json");
            httpPost.setHeader("Accept-Charset", "UTF-8");

            CloseableHttpResponse respons = client.execute(httpPost);

            System.out.println("  respons.getStatusLine().getStatusCode()  " + respons.getStatusLine().getStatusCode());
        }

"{\"chat_id\":\"" + c_id+ "\",\"text\":\"Hi\"}";

{"chat_id":555555,"text":"Hi","reply_markup":{"InlineKeyboardButton":[{"text":"A"}]}}

{
  "chat_id": 555555,
  "text": "Hi",
  "reply_markup": {
    "inline_keyboard": [
      [
        {
          "text": "A"
        },
        {
          "text": "B"
        }
      ]
    ]
  }
}

{
  "chat_id": 555555,
  "text": "Hi",
  "reply_markup": {
    "inline_keyboard": [
      [
        {
          "text": "A",
          "callback_data": "A1"
        },
        {
          "text": "B",
          "callback_data": "C1"
        }
      ]
    ]
  }
}

The fixed IP address which will be used to send webhook requests instead of the IP address resolved through DNS

 {"ok":true,"result":true,"description":"Webhook was set"}