<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Groups\Item\CalendarView\CalendarViewRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new CalendarViewRequestBuilderGetRequestConfiguration();
$headers = [
'Prefer' => 'outlook.body-content-type="text"',
];
$requestConfiguration->headers = $headers;
$queryParameters = CalendarViewRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->startDateTime = "2017-01-01T19:00:00-08:00";
$queryParameters->endDateTime = "2017-10-01T19:00:00.00-08:00";
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->groups()->byGroupId('group-id')->calendarView()->get($requestConfiguration)->wait();