I am trying to connect my Google Sheet to a PHP script using a Google Apps Script. This requires sending payload with the UrlFetchApp function. And, this is where the connection betweenn Script and PHP goes wrong. 
The connection works, when I replace the echo value in the PHP script to a non variable, there is a response. Also, my response code is 200. 
But, sending or reading my payload is the problem. 
Google Apps Script:
var payload = {"A": "12345"};
var url = 'myurl/stats.php'
var response = UrlFetchApp.fetch(
        url,
        {
          "method": "GET",
          "contentType": "application/json",
          "payload": JSON.stringify(payload),
        }
      );
var responseCode = response.getResponseCode();
var responseBody = response.getContentText();
Logger.log(responseCode);
Logger.log(responseBody); 
PHP:
<?php 
$A = $_GET["A"];
echo json_encode("Hello: ".$A);
?>
Note: Using a browser, this PHP script is working.
I expect responseBody to be "Hello: 12345" but the actual output is "Hello: "
 
    