partial         void CopyExtraPropertiesToClone(ExternalSourceMetadata clone, bool includeLocalProperties);
 public ExternalSourceMetadata Clone(bool includeLocalProperties)
 {
     var c = new ExternalSourceMetadata
             {
                 End = End,
                 Id = Id,
                 InitialFieldValues = InitialFieldValues,
                 Key = Key,
                 Name = Name,
                 Widgets = Widgets,
                 CompatibleWithSourceKeys = CompatibleWithSourceKeys.ToList(),
             };
     CopyExtraPropertiesToClone(c, includeLocalProperties);
     return c;
 }