Description:
------------
From client in CURL:

$ch = curl_init();
$data = '{"test":"hello"}';
curl_setopt($ch, CURLOPT_URL, 'http://localhost');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json', 'Content-Length: '.strlen($data)]);
curl_setopt($ch, CURLOPT_TIMEOUT, 5);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
$output = curl_exec($ch);
var_dump($output);
curl_close($ch);

From server
var_dump($_SERVER["CONTENT_TYPE"], $_REQUEST, $_POST);
//"string(16) "application/json" array(0) { } array(0) { } " 

But file_get_contents("php://input") is populated

Tied the same with an Ajax call and the result is identical