title: GWT IncompatibleRemoteServiceException
body: <p>Straight forward but maddening, I get this error on my RPC call:    </p>
  
  <p>An IncompatibleRemoteServiceException was thrown while processing this call.
      com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException: Invalid type   signature for com.milkrun.core.dto.UserBasket</p>
  
  <p>Here is the class causing the issue:</p>
  
  <pre><code>public class UserBasket implements Serializable{
  
       private static final long serialVersionUID = -6761554796753637352L;
  
      public int userBasketID;
      public String description;
      public String userID;
  
      public List&lt;BasketItem&gt; items;
  
      public String createUserId;
      public Timestamp createTs;
       public String lastUpdateUserId;
      public Timestamp lastUpdateTs;
      public Timestamp effStartTs;
      public Timestamp effStopTs;
  
  }
  </code></pre>
  
  <p>And the type BasketItem:</p>
  
  <pre><code>public class BasketItem implements Serializable {
  
  
  private static final long serialVersionUID = -17764683871112216L;
  
  public int basketItemID;
  
  public String upc;
  public String description;
  public String brandName;
  
  public BigDecimal price;
  
  public String createUserId;
  public Timestamp createTs;
  public String lastUpdateUserId;
  public Timestamp lastUpdateTs;
  public Timestamp effStartTs;
  public Timestamp effStopTs;
  
  }
  </code></pre>
  
  <p>I'm not sure where I'm going wrong and I'd rather not use IsSerializable as these DTOs are in a project shared by an android app too and IsSerializable is part of the GWT stack.</p>