title: Automapper sets an array property to a zero-length array rather than null
body: <p>I'm using Automapper to copy values from one instance to another, and I'm finding that if the class has an array property, and the source instance has the property set to <code>null</code>, Automapper sets the destination property to a zero-length array instead of <code>null</code> as I expected.  </p>
  
  <p>Is there a way to configure Automapper to set the destination to <code>null</code> when the source is <code>null</code>?</p>
  
  <p>In case my explanation is unclear, the following code illustrates what I'm trying to describe:</p>
  
  <pre><code>public class Test
  {
      public byte[] ByteArray { get; set; }
      public int? NullableInt { get; set; }
      public int Int { get; set; }
  }
  
  class Program
  {
      static void Main(string[] args)
      {
          Mapper.CreateMap&lt;Test, Test&gt;();
  
          var test1 = new Test { Int = 123, NullableInt = null, ByteArray = null };
          var test2 = Mapper.Map&lt;Test&gt;(test1);
  
          // test1:  Int == 123, NullableInt == null, ByteArray == null
          // test2:  Int == 123, NullableInt == null, ByteArray == byte[0]  &lt;-- expect this to be null
      }
  }
  </code></pre>