Description
The Microsoft.Extensions.Options.DataAnnotations library only exists because it has a dependency on System.ComponentModel.Annotations. Since System.ComponentModel.Annotations wasn't in netstandard2.0 by default, the code in this library was split into its own package instead of being added to Microsoft.Extensions.Options.
However, recently we've added a dependency from Microsoft.Extensions.Options netstandard2.0 to System.ComponentModel.Annotations in the 6.0.0-preview5.21301.5 NuGet package. It looks like this was added by a combination of #52084 + #35606.
Also, as of 6.0, System.ComponentModel.Annotations is now part of the netX.0+ TFM by default. It is no longer a separate NuGet package.
With #82749, we are doubling down on this dependency, and fully adding System.ComponentModel.Annotations code to Microsoft.Extensions.Options.
Given all these changes, it doesn't make sense to keep Microsoft.Extensions.Options.DataAnnotations as a separate library/NuGet package. It is just an extra package, assembly, etc and can be merged into Microsoft.Extensions.Options.
I'm not exactly sure how to do this with NuGet packages. I know we will need TypeForwardedTo attributes in order to keep back compat working. Does that mean we will need to keep shipping a NuGet package for Microsoft.Extensions.Options.DataAnnotations with just the TypeForwardedTo attribute? Maybe we only need to ship 1 more - 8.0.0 with TypeForwardedTo and then it can be dead-ended after that?