title: Reference to type 'AuthenticationTicket' claims it is defined in 'Microsoft.AspNetCore.Authentication', but it could not be found
body: <p>I have an ASP.NET Core 2 application, right now I am having some issues with migrating the code that I have from Core 1x. Here we have a small piece of code. I am having this errors, can anybody tell me if anything changed in this matter please?
  PS: All four errors are the same:</p>
  
  <blockquote>
    <p>Reference to type 'AuthenticationTicket' claims it is defined in
    'Microsoft.AspNetCore.Authentication', but it could not be found.</p>
  </blockquote>
  
  <pre><code>[errors in the code][1]
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/xJNXy.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <pre><code> private async Task&lt;AuthenticationTicket&gt; CreateTicketAsync(OpenIdConnectRequest request, ApplicationUser user, AuthenticationProperties properties = null)
      {
          // Create a new ClaimsPrincipal containing the claims that
          // will be used to create an id_token, a token or a code.
          var principal = await _signInManager.CreateUserPrincipalAsync(user);
  
          // Create a new authentication ticket holding the user identity.
          var ticket = new AuthenticationTicket(principal, new AuthenticationProperties(), OpenIdConnectServerDefaults.AuthenticationScheme);
          ticket.SetResources(request.GetResources());**// ERROR IN THIS LINE**
  
          //if (!request.IsRefreshTokenGrantType())
          //{
          // Set the list of scopes granted to the client application.
          // Note: the offline_access scope must be granted
          // to allow OpenIddict to return a refresh token.
          ticket.SetScopes(new[] **// ERROR IN THIS LINE**
          {
                  OpenIdConnectConstants.Scopes.OpenId,
                  OpenIdConnectConstants.Scopes.Email,
                  OpenIdConnectConstants.Scopes.Profile,
                  OpenIdConnectConstants.Scopes.OfflineAccess,
                  OpenIddictConstants.Scopes.Roles
              }.Intersect(request.GetScopes())); **// ERROR IN THIS LINE**
          //}
  }
  </code></pre>
  
  <p>UPDATE:
  <a href="https://i.stack.imgur.com/Ch4lJ.png" rel="nofollow noreferrer">Nuget references</a></p>