PHP AWS SDK - S3 StreamWrapper with ACL and ContentType

app.php

<?php
//autoloader
require_once __DIR__ . '/vendor/autoload.php';

use Aws\S3\S3Client;
use Aws\S3\Enum\CannedAcl;
//init client
$s3Client = S3Client::factory(array(
    'key'       => '<key>',
    'secret'    => '<secret>',
    'region'    => 'eu-west-1'
));

//register wrapper
$s3Client->registerStreamWrapper();

define('S3_PATH', 's3://<bucket>/aws-acl-test/');

function createRandomFileWithPermission($acl, $filename)
{
    //create content
    $string = '';
    for ($i=0; $i < 4096; $i++) {
        $char = '';
        switch (rand(0, 2)) {
            //A-Z
            case 0:
                $char = chr(rand(65, 90));
                break;
            //a-z
            case 1:
                $char = chr(rand(97, 122));
                break;
            //0-9
            case 2:
                $char = chr(rand(97, 122));
                break;

        }
        $string .= $char;
    }

    //create stream context
    $context = stream_context_create(array(
        's3' => array(
            'ACL' => $acl,
            'ContentType' => 'text/plain'
        )
    ));

    //create file with file_put_contents
    file_put_contents(S3_PATH . 'file_put_contents_'.$filename.'.txt', $string, null, $context);

    //create file with fopen
    $stream = fopen(S3_PATH . 'fopen_'.$filename.'.txt', 'w', null, $context);

    fwrite($stream, $string);
    fclose($stream);
}

createRandomFileWithPermission(CannedAcl::PRIVATE_ACCESS, 'private_access');
createRandomFileWithPermission(CannedAcl::PUBLIC_READ, 'public_read');
createRandomFileWithPermission(CannedAcl::PUBLIC_READ_WRITE, 'public_read_write');
createRandomFileWithPermission(CannedAcl::AUTHENTICATED_READ, 'authenticated_read');
createRandomFileWithPermission(CannedAcl::BUCKET_OWNER_FULL_CONTROL, 'bucket_owner_full_control');
createRandomFileWithPermission(CannedAcl::BUCKET_OWNER_READ, 'bucket_owner_read');

composer.json

{
    "name": "fridokoch/aws-acl-test",
    "require": {
        "aws/aws-sdk-php": "dev-master"
    },
    "license": "MIT",
    "authors": [
        {
            "name": "Frido Koch",
            "email": "info@fridokoch.de"
        }
    ],
    "minimum-stability": "dev"
}