title: Optional parameters in SignalR 1.x Hub Method
body: <p>i recently installed <code>SiganlR 1.x</code> in .net 4.0 <code>MVC4</code> application
  and sample methods works fine when i use as it is</p>
  
  <p>but i want to pass an optional parameter to hub method which can be <code>null</code> or <code>undefined</code> or <code>empty</code></p>
  
  <p>so added new parameter <code>toUser</code> to the hub method</p>
  
  <pre><code>public class ContosoChatHub : Hub
  {
      public void NewContosoChatMessage(string name, string message, string toUser = null)
      {
          Clients.All.addContosoChatMessageToPage(name, message);
      }
  }
  
  //javascript
  contosoChatHubProxy.server.newContosoChatMessage(name, messsage);
  //or
  contosoChatHubProxy.server.newContosoChatMessage(name, messsage, '');
  </code></pre>
  
  <p>when the above script invoked, im getting Error at client side</p>
  
  <pre><code>Argument cannot be null or empty
  Parameter name: toUser
  </code></pre>
  
  <p>need some expertise. 
  Thank you.</p>