<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Organization\Item\Branding\BrandingRequestBuilderPatchRequestConfiguration;
use Microsoft\Graph\Beta\Generated\Models\OrganizationalBranding;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new OrganizationalBranding();
$requestBody->setSignInPageText('Default');
$requestBody->setUsernameHintText('DefaultHint');
$requestConfiguration = new BrandingRequestBuilderPatchRequestConfiguration();
$headers = [
'Accept-Language' => '0',
];
$requestConfiguration->headers = $headers;
$result = $graphServiceClient->organization()->byOrganizationId('organization-id')->branding()->patch($requestBody, $requestConfiguration)->wait();