<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Compliance\Ediscovery\Cases\Item\SourceCollections\Item\SourceCollectionItemRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new SourceCollectionItemRequestBuilderGetRequestConfiguration();
$queryParameters = SourceCollectionItemRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->expand = ["addToReviewSetOperation","custodianSources","lastEstimateStatisticsOperation"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->compliance()->ediscovery()->cases()->byCaseId('case-id')->sourceCollections()->bySourceCollectionId('sourceCollection-id')->get($requestConfiguration)->wait();