<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Models\Attachment;
use Microsoft\Graph\Beta\Generated\Models\Message;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new Attachment();
$requestBody->setOdataType('#Microsoft.OutlookServices.ItemAttachment');
$requestBody->setName('name-value');
$additionalData = [
'item' => [
'@odata.type' => 'microsoft.graph.message',
],
];
$requestBody->setAdditionalData($additionalData);
$result = $graphServiceClient->me()->events()->byEventId('event-id')->attachments()->post($requestBody)->wait();