LinkedIn API - Couldn't parse share document - Json - php

Question

So i'm working with the LinkedIn API and i'm trying to share something to my wall but i'm getting the following error:
Couldn't parse share document: error: Unexpected end of file after null
I think something is going wrong with with adding the HTTPHEADERS:
Content-Type: application/json
x-li-format: json
So this is what i'm trying to do:
$parameters = array("comment" => "Check out developer.linkedin.com, I'm currently testing it myself!",
"content" => array( "title" => "LinkedIn Developers Resources",
"description" => "Leverage LinkedIn's APIs to maximize engagement",
"submitted-url" => "https://developer.linkedin.com",
"ubmitted-image-url" => "https://example.com/logo.png"
),
"visibility" => array("visibility" => "anyone")
);
$result = $connection->post("people/~/shares", $parameters);
var_dump($result);
var_dump($result); shows the error message above.
And these are the functions i'm using:
public function post($path, $parameters = []){
$url = $this->createUrl($path);
$parameters = json_encode($parameters);
return $this->curlRequest('POST', $url, $parameters);
}
this is the post function, wich is using the following functions:
private function createUrl($path) {
return self::API_HOST . "/v" . self::API_VERSION . "/" . $path . "?" . self::FORMAT;
}
private function curlRequest($method, $url, $postData = NULL, $accessToken = false){
$curl = curl_init();
switch($method) {
case 'GET':
break;
case 'POST':
curl_setopt($curl, CURLOPT_POST, true);
if($accessToken) {
curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query($postData));
} else {
curl_setopt($curl, CURLOPT_POSTFIELDS, $postData);
}
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type: application/json', 'x-li-format: json'));
break;
}
if ($accessToken) {
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type: application/x-www-form-urlencoded'));
} else {
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $this->accessToken));
}
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_URL, $url);
$result = curl_exec($curl);
curl_close($curl);
return json_decode($result, true);
}
Hope someone can help me with this problem.