title: Set a Single Select control as required in Google Data Studio
body: <p>I have a filter control with style "Single Select". This filter has two options: "New Users" and "All Users", by default its value is "All Users".</p>
  
  <p>Now I need to force one of the options is always selected. Is there a way to achieve this? It's something like set this control as "required".</p>