Failed to create new credentials

Question

I am currently trying to open a field for an authenticated user, but I am having difficulty trying to add a new requirement for an authenticated user.

In MVC5, I would do something similar to the following:

public class ApplicationUser : IdentityUser
{
    public string FullName { get; set; }
    public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)
    {
        // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
        var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
        // Add custom user claims here
        userIdentity.AddClaim(new Claim("FullName", FullName));
        return userIdentity;
    }
}

When I try to do this in MVC6, I run into problems with the lack of objects and methods. The creators of CreateIdentityAsync () and DefaultAuthenticationTypes seem to be missing or, therefore, talking about visual studio, and when I delve into the Identity source, I see that CreateIdentityAsync no longer exists, however I cannot find anything about DefaultAuthenticationTypes.

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