if true, the codec will also not emit the _case field during writing of default
case class/object (analogous to transientDefault).
if true, the codec will also not emit the _case field during writing of default
case class/object (analogous to transientDefault).
When materializing a
GenCodecfor sealed hierarchy with@flattenannotation, you can use this annotation on one of case classes or objects to mark it as the default one. If during deserialization the codec is unable to find the_casefield and determine the case class/object to deserialize, it will try to deserialize the data to the class/object marked with this annotation.This is useful for retaining backwards compatibility with serialized format when refactoring code and replacing a simple case class with a sealed hierarchy.