While reading the documentation for adding custom claims, I don’t understand what the use is of ‘always’ adding the identity.

Instead of the code sample provided

ClaimsIdentity claimsIdentity = new ClaimsIdentity();
var claimType = "myNewClaim";
if (!principal.HasClaim(claim => claim.Type == claimType))
{
    claimsIdentity.AddClaim(new Claim(claimType, "myClaimValue"));
}

principal.AddIdentity(claimsIdentity);
return Task.FromResult(principal);

I was expecting something more along the lines of

var claimType = "myNewClaim";
if (!principal.HasClaim(claim => claim.Type == claimType))
{
    ClaimsIdentity claimsIdentity = new ClaimsIdentity();
    claimsIdentity.AddClaim(new Claim(claimType, "myClaimValue"));
    principal.AddIdentity(claimsIdentity);
}

return Task.FromResult(principal);

Why add the identity if the principal already has the claim?