Andriy Tolstoy

Reuse already existing check in the [AuthenticationPropertiesExtensions.AddClientId](https://github.com/DuendeSoftware/IdentityServer/blob/main/src/IdentityServer/Extensions/AuthenticationPropertiesExtensions.cs#L101) method.

remove unnecessary distinct method

3

[Enumerable.Union](https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.union?view=net-8.0#system-linq-enumerable-union-1(system-collections-generic-ienumerable((-0))-system-collections-generic-ienumerable((-0)))) method already excludes duplicates. > Returns An [IEnumerable](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.ienumerable-1?view=net-8.0) that contains the elements from both input sequences, excluding duplicates. --- ``` IEnumerable first = ["a", "b"]; IEnumerable second = ["a",...

use static equals method to avoid exception

2

`user.Password` could be null.