Microsoft.Extensions.Identity.Stores by Microsoft

<PackageReference Include="Microsoft.Extensions.Identity.Stores" Version="2.1.0" />

 IdentityUserRole<TKey>

public class IdentityUserRole<TKey> where TKey : IEquatable<TKey>
Represents the link between a user and a role.
public virtual TKey RoleId { get; set; }

Gets or sets the primary key of the role that is linked to the user.

public virtual TKey UserId { get; set; }

Gets or sets the primary key of the user that is linked to a role.