Creating a Group at project level - GraphGroupCreationContext issue

Just want to verify if this API is ready to be consumed and used or this particular one is still at preview?

Looks like the request body and the model doesn't have the same attributes:
In here, there's a displayName and description:
https://docs.microsoft.com/en-us/rest/api/azure/devops/graph/groups/create?view=azure-devops-rest-5.0#create_a_group_at_the_project_level

But on the client, where it asks for a graphgroupcreationcontext, it only asks for a storagekey. And the warning here states that we shouldn't use this for creation of a group:
https://docs.microsoft.com/en-us/rest/api/azure/devops/graph/groups/create?view=azure-devops-rest-5.0#graphgroupcreationcontext

How can I create a group in a project level given the api above?

從 GraphGroupCreationContext 用戶端模型開始，並將其與連結的 Azure DevOps REST 專案層級群組建立文件進行比較。判斷模型與文件中所記載的要求屬性是否一致，並確認建立專案層級群組的支援方式。