title: How do I skip/delete an item in the ItemProcessor?
body: <p>I want to be able to delete an item while processing it if it fits a specific logic. For example, if the item doesn't contain a value I'm looking for, I don't want to that item to be written out to the file. </p>
  
  <p>I'm currently using a class which implements <code>ItemProcessor&lt;T,T&gt;</code>.</p>
  
  <p>Do I just return null?</p>