The Microsoft Online tenant being used to access data. If not specified, your default tenant will be used.
The Microsoft Online tenant being used to access data. For instance, contoso.onmicrosoft.com. Alternatively, specify the tenant id. This value is the directory Id in the Azure Portal > Azure Active Directory > Properties.
Typically it is not necessary to specify the Tenant. This can be automatically determined by Microsoft when using the OAuthGrantType set to CODE (default). However, it may fail in the case that the user belongs to multiple tenants. For instance, if an Admin of domain A invites a user of domain B to be a guest user. The user will now belong to both tenants. It is a good practice to specify the Tenant, although in general things should normally work without having to specify it.
The Tenant is required when setting OAuthGrantType to CLIENT. When using client credentials, there is no user context. The credentials are taken from the context of the app itself. While Microsoft still allows client credentials to be obtained without specifying which Tenant, it has a much lower probability of picking the specific tenant you want to work with. For this reason, we require Tenant to be explicitly stated for all client credentials connections to ensure you get credentials that are applicable for the domain you intend to connect to.