Office 365 API - Request returned HTTP error 400 - rest

Question

I'm trying to follow a tutorial where I pull mail and calendar events from the Office 365 API. I was able to pull mail but when I try to pull calendar events I get back error 400 which, from some Googling, is apparently that one of my headers being too long. I put a var_dump(getallheaders()); and can see the following:
array (size=10)
'Host' => string 'localhost:9999' (length=14)
'Connection' => string 'keep-alive' (length=10)
'Pragma' => string 'no-cache' (length=8)
'Cache-Control' => string 'no-cache' (length=8)
'Accept' => string 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' (length=74)
'Upgrade-Insecure-Requests' => string '1' (length=1)
'User-Agent' => string 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.106 Safari/537.36' (length=121)
'Accept-Encoding' => string 'gzip, deflate, sdch' (length=19)
'Accept-Language' => string 'en-US,en;q=0.8' (length=14)
'Cookie' => string 'PHPSESSID=286082ac61749c4e351c1218495859bb; SQLiteManager_currentLangue=2' (length=73)
This all looks fine to me. What am I missing?
EDIT - when I do $response = curl_exec($curl); followed by var_dump($response); I get this:
string '{"error":{"code":"RequestBroker-ParseUri","message":"The $orderby expression must evaluate to a single value of primitive type."}}' (length=130)
The function with $orderby expression is this:
public static function getEvents($access_token, $user_email) {
$getEventsParameters = array (
// Only return Subject, Start, and End fields
"\$select" => "Subject,Start,End",
// Sort by Start, oldest first
"\$orderby" => "Start",
// Return at most 10 results
"\$top" => "10"
);
$getEventsUrl = self::$outlookApiUrl."/Me/Events?".http_build_query($getEventsParameters);
return self::makeApiCall($access_token, $user_email, "GET", $getEventsUrl);
}

Answer 1

Ok. The issue is that we changed the type for the Start property. It's now a complex type. You want to sort on the DateTime property of the Start property, so you'd want to change this line:
"\$orderby" => "Start",
To this:
"\$orderby" => "Start\DateTime",
I thought we had updated the tutorials, but I see that the PHP one isn't updated. I'll work on getting that fixed today!