title: C# - How can I check if a Type is concrete?
body: <p>I have a collection of Types and I want to filter out every Type that is not concrete.</p>
  
  <p>I can see that I can check isAbstract and isInterface to catch most non-concretes, but is this going to miss anything?</p>
  
  <p>Is there an "isConcrete" property?</p>