title: Morphia storing empty values
body: <p>I am using Morphia+MongoDB as a backend for a simple CRUD input mask.</p>
  
  <p>I prepare the framework the simplest possible way, creating a new MongoClient and initializing Morphia like that:</p>
  
  <pre><code>Morphia morphia = new Morphia();
  morphia.mapPackage("it.trew.omg.model");
  </code></pre>
  
  <p>Both instances are injected into a DAO:</p>
  
  <pre><code>public class ClientiDao extends BasicDAO&lt;Cliente, String&gt;
  </code></pre>
  
  <p>My entity is still pretty simple:</p>
  
  <pre><code>@Entity("clienti")
  public class Cliente {
  
      @Id ObjectId id;
  
      String name;
      String address;
      String city;
      String state;
      String email;
  
      public Cliente() {
  
      }
  
  // getters+setters
  
  }
  </code></pre>
  
  <p>Let's say I create a Cliente by just filling the name inside my form.</p>
  
  <p>When a controller calls the save method, the operation is successful:</p>
  
  <pre><code>getClientiDao().save(cliente);
  </code></pre>
  
  <p>But when I query the 'clienti' collection from the mongo console I get this:</p>
  
  <pre><code>{ "_id" : ObjectId("547edf630364677dd2f911b8"), "className" : "it.trew.omg.model.Cliente", "name" : "Fabio Bozzo", "indirizzo" : "", "citta" : "", "cap" : "", "provincia" : "", "stato" : "", "email" : "", "telefono" : "", "fax" : "", "note" : "" }
  </code></pre>
  
  <p>I thought that empty fields would not have been inserted. Is there something wrong?</p>
  
  <p>Versions are:</p>
  
  <pre><code>&lt;dependency&gt;
              &lt;groupId&gt;org.mongodb&lt;/groupId&gt;
              &lt;artifactId&gt;mongo-java-driver&lt;/artifactId&gt;
              &lt;version&gt;2.12.4&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.mongodb.morphia&lt;/groupId&gt;
              &lt;artifactId&gt;morphia&lt;/artifactId&gt;
              &lt;version&gt;0.108&lt;/version&gt;
          &lt;/dependency&gt;
  </code></pre>