Google Contacts API Not Returning System Groups

https://www.google.com/m8/feeds/groups/default/full/6

That should return a list of all the contacts in the system group My Contacts, but it says "Group not found."

When I request a list of all the contact groups, it only returns the user-defined groups.

When I request a list of all my contacts, it gives me all my contacts, but it does not tell me what group they are in unless it's a user-defined group.

Any ideas as to what I'm doing wrong?

Edit: I redirect here

https://accounts.google.com/o/oauth2/auth?client_id=819467938951.apps.googleusercontent.com&redirect_uri=http://subomain.website.com/back.html&scope=https://www.google.com/m8/feeds/&response_type=code

And this is the source of back.html (modified from http://php.dzone.com/news/execute-http-post-using-php-cu)

<?php
$token = $_GET["code"];

$url = 'https://accounts.google.com/o/oauth2/token';
$fields = array(
        'code'=>urlencode($token),
        'client_id'=>urlencode("819467938951.apps.googleusercontent.com"),
        'client_secret'=>urlencode("secret key"),
        'redirect_uri'=>urlencode("http://subdomain.website.com/back.html"),
        'grant_type'=>urlencode("authorization_code")
    );

//url-ify the data for the POST
foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }
rtrim($fields_string,'&');

//open connection
$ch = curl_init();

//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_POST,count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);


//execute post
$result = curl_exe开发者_C百科c($ch);

//close connection
curl_close($ch);

$result=json_decode($result, true);

$access_token = $result["access_token"];

print_r(file_get_contents("https://www.google.com/m8/feeds/groups/default/full/6?access_token=" . $access_token));
?>

retrieve all contacts from a group in PHP

Once I set v=2, the system groups finally showed up!

https://www.google.com/m8/feeds/groups/default/full?v=2

To get the contacts in a group, set group = the group url

https://www.google.com/m8/feeds/contacts/default/full?v=2&group=http://www.google.com/m8/feeds/groups/default/base/6