Fix generic type handling

[mentallabyrinth]

Love the direction Microsoft.AspNetCore.OpenApi.SourceGenerators is going, but there's a bug when extracting comments from types that support generics. The issue is in https://github.com/aspnet/AspLabs/blob/main/src/OpenApiXmlCommentGenerator/gen/XmlCommentGenerator.Parser.cs, specifically in these lines of code:

var typeInfo = type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
var typeInfo = property.ContainingType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);

To fix this, I've added a new method ToNormalizedDisplayString to INamedTypeSymbolExtensions.cs. The method checks if the type is generic - if so, it constructs an unbounded generic type (which works well for the comment caching strategy) and uses that for the display name. Otherwise, it uses the general type:

public static string ToNormalizedDisplayString(this INamedTypeSymbol symbol, SymbolDisplayFormat? format = null)  
{  
    if (symbol.IsGenericType)  
    {        var genericType = symbol.ConstructUnboundGenericType();  
        return genericType.ToDisplayString(format);  
    }  
    return symbol.ToDisplayString(format);  
}

Looking forward to the general release. Thanks for your efforts!

[mentallabyrinth]

@dotnet-policy-service agree