<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Models\CertificateAuthorityAsEntity;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new CertificateAuthorityAsEntity();
$requestBody->setIsRootAuthority(true);
$result = $graphServiceClient->directory()->certificateAuthorities()->certificateBasedApplicationConfigurations()->byCertificateBasedApplicationConfigurationId('certificateBasedApplicationConfiguration-id')->trustedCertificateAuthorities()->byCertificateAuthorityAsEntityId('certificateAuthorityAsEntity-id')->patch($requestBody)->wait();