Purpose of 'Microsoft.Identity.Web.UI' doesn't seem clear enough

[julealgon]

'Microsoft.Identity.Web.UI' was added alongside 'Microsoft.Identity.Web' to my REST API project once I configured Azure AD via Connected Services. This package is not installed by default on the project template when enabling AAD, so I'm wondering if it is added by mistake by Connected Services setup.

It is not clear to me exactly what this package is for, here is the current description:

This package enables UI for ASP.NET Core Web apps that use Microsoft.Identity.Web.

What exactly is "enabling UI"? How do I use it? Does this only make sense for non-API projects? Is there any reason to ever have this referenced in a pure REST API project without views?

I'm going to remove the package for now as it seems useless to me, but it would be nice if:

1. The documentation on the package was a bit more explicit about what exactly it is for and how to use it
2. The ConnectedService integration for Azure AD didn't add this package for pure API projects