title: Compare with null Date in range
body: <pre><code>@Document
  public class Product extends Item {
      private Date onlineDate;
  
      private Date offlineDate;
  }
  </code></pre>
  
  <p>Data</p>
  
  <pre><code>Product {
      onlineDate : some date
      offlineDate : null
  }
  </code></pre>
  
  <p>below query return 0 hits</p>
  
  <pre><code>query.addCriteria(Criteria.where("onlineDate").lte(date).and("offlineDate").gte(date))
  </code></pre>
  
  <p>but below query returns results</p>
  
  <pre><code>query.addCriteria(Criteria.where("onlineDate").lte(date))
  </code></pre>
  
  <p>is this something that I am not allowed to compare with null date.</p>