title: AspNetCore.SignalR: 'IClientProxy' does not contain a definition for 'InvokeAsync'
body: <p>I have successfully integrated SignalR.AspNetCore into my AbpZero template. everything works fine. However when I tried to add a hub into my application like what has been described in the <a href="https://aspnetboilerplate.com/Pages/Documents/SignalR-AspNetCore-Integration" rel="noreferrer">document</a>, I am getting the following error on </p>
  
  <pre><code>public async Task SendMessage(string message)
  {
      await Clients.All.InvokeAsync("getMessage", string.Format("User {0}: {1}", AbpSession.UserId, message));
  }
  </code></pre>
  
  <blockquote>
    <p>Error CS1061  'IClientProxy' does not contain a definition for 'InvokeAsync' and no extension method 'InvokeAsync' accepting a first argument of type 'IClientProxy' could be found (are you missing a using directive or an assembly reference?) </p>
  </blockquote>