<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\RoleManagement\Directory\RoleAssignments\Item\UnifiedRoleAssignmentItemRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new UnifiedRoleAssignmentItemRequestBuilderGetRequestConfiguration();
$queryParameters = UnifiedRoleAssignmentItemRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->expand = ["roleDefinition"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->roleManagement()->directory()->roleAssignments()->byUnifiedRoleAssignmentId('unifiedRoleAssignment-id')->get($requestConfiguration)->wait();