<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Users\Item\Events\Item\EventItemRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new EventItemRequestBuilderGetRequestConfiguration();
$headers = [
'Prefer' => 'outlook.body-content-type="text"',
];
$requestConfiguration->headers = $headers;
$queryParameters = EventItemRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->select = ["subject","body","bodyPreview"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->me()->events()->byEventId('event-id')->get($requestConfiguration)->wait();