Logging, Interop, Regex and JSON generators include // <auto-generated/> at the top of their emitted .g.cs.
EventSource generator does not.

Logging, Regex and JSON generators include something like [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Extensions.Logging.Generators", "42.42.42.42")]
EventSource and Interop generators do not.

After #64534, all 5 of them use .g.cs extensions when writing to disk.

@jaredpar is it reasonable that all three of these should be required by convention in generators? I'm not sure what effect each one has. For example, we discovered that coverlet looks for .g.cs.