DateFormatConverter is the only class from TypeConverter family that didn't implement java.io.Serializable.

package org.zkoss.zkplus.databind;

public interface TypeConverter

{ ... }
public class DateFormatConverter implements TypeConverter { ... }

public class ListModelConverter implements TypeConverter, java.io.Serializable

{ ... }
public class RadiogroupSelectedItemConverter implements TypeConverter, java.io.Serializable { ... }

public class SelectedComboitemConverter implements TypeConverter, java.io.Serializable

{ ... }
public class SelectedItemConverter implements TypeConverter, java.io.Serializable { ... }

public class TabboxSelectedTabConverter implements TypeConverter, java.io.Serializable

{ ... }