func ProcessJsonForRead(fqn shared.Fqn, j []byte) ([]byte, error)
Add missing AddableFields to read json. Remove found RemovableFields from read json.
func RegisterAddableField(fqn shared.Fqn, aField *cshared.AddableField) error
func RegisterRemovableField(fqn shared.Fqn, fieldName cshared.FieldName) error