SmartGWT 4.0 Upgrade with GWT 2.2.0 - Class Not Found

[robert.jackson@nscorp.com]

Current we are running GWT 2.2.0 and SmartGWT 3.1 on Java 1.6 I am
attempting to upgrade to SmartGWT 4.0. However when I execute the GWT build I get the following error.

[ERROR] Errors in 'jar:file:/opt/opd/zfxb6work/drivers/smargwt/smartgwt.jar!/com/smartgwt/client/util/LogicalDate_CustomFieldSerializer.java'
[ERROR] Line 3: The import com.google.gwt.user.client.rpc.CustomFieldSerializer cannot be resolved
[ERROR] Line 8: CustomFieldSerializer cannot be resolved to a
type

I searched our application's GWT jars and the com.google.gwt.user.client.rpc.CustomFieldSerializer file does not exist.

How do I resolve this issue without upgrading the apps GWT version at this time?

[Isomorphic]

It looks like you're using GWT-RPC in combination with an old version of GWT that did not support key APIs that *must* be present to avoid GWT-RPC incorrectly modifying dates during data transmission.

Unfortunately you'll need to either:

1. update GWT

OR

2. stop using GWT-RPC (which we strongly recommend against in general, for very very good reasons).