title: Validating C# base class constructor parameter
body: <p>After running Code Analysis in VS2010 beta (FxCop for previous versions) I'm getting the following warning:</p>
  
  <blockquote>
    <p>In externally visible method
    'Identity.Identity(WindowsIdentity)',
    validate parameter 'windowsIdentity'
    before using it.</p>
  </blockquote>
  
  <p>The constructor is:</p>
  
  <pre><code>public Identity(WindowsIdentity windowsIdentity)
           : base(windowsIdentity.Token)
  {
           init();
  }
  </code></pre>
  
  <p>for a class defined as:</p>
  
  <pre><code>public class Identity : WindowsIdentity
  </code></pre>
  
  <p>My question is, how do I validate the windowsIdentity parameter?  Should I validate it in the constructor, and throw an exception, or is there a better way to call this?</p>