Remove pubternal types from Kestrel

[jkotalik]

MVC recently made all pubinternal types in MVC internal via #4932. As a reminder, pubinternal types are types that are declared as public but put in an .Internal namespace.

In ASP.NET Core 3.0, we should do the same in Kestrel, specifically for the Microsoft.AspNetCore.Server.Kestrel.Core.Internal namespace. Reference assemblies will also show any pubinternal changes.

cc @muratg @halter73 @Tratcher

[Tratcher]

Just Kestrel? I would expect this to extend to most of AspNetCore.

[jkotalik]

I mean sure, but let's start somewhere. The issue for MVC was individualized.

[muratg]

With the targetting pack work, I think this is more critical now. Making breaking changes will be harder in these technically public types.

@Eilon @DamianEdwards @davidfowl thoughts?

[Tratcher]

@jkotalik Think bigger 😁

[halter73]

Definitely not just Kestrel, though I've heard through the grapevine that EF actually likes pubternal.

[Eilon]

EF Core is sticking with pubternal. But MVC removed a lot of pubternal (either make true internal or make true public). Up to each feature area to make a call.

[pranavkm]

#8308 if there's interest in doing for everything that ships in the targeting pack

[jkotalik]

Thanks @pranavkm <3.

[benaadams]

You'll break the TE Platform tests though as that uses pubternal apis /cc @davidfowl

[benaadams]

If the used apis were made public they'd have to switch from Span<byte> to ReadOnlySpan<byte>; which they should do eventually anyway.

[Eilon]

TE Platform tests definitely shouldn't be using pubternal types 😭