public class UsersController { private readonly IUsersService _userService; public UsersController(IUsersService userService) { _userService = userService; } [HttpPost("login")] public IActionResult Login([FromBody] UserCredentials credentials) { if (!_userService.Authenticate(credentials.Username, credentials.Password)) { return Unauthorized(); } // user is authenticated, proceed with login logic // ... } }In this example, the UsersController class has a Login method that takes in user credentials as a payload and calls the IUsersService Authenticate method to authenticate the user. If the authentication fails, the method returns an Unauthorized response. The package library used for this code example could be any .NET library that provides user authentication services, such as Microsoft.AspNetCore.Identity, SimpleAuthentication, or IdentityModel.AspNetCore.