@Jacksonized now supports both Jackson2 and Jackson3; you'll get a warning until you configure which one (or even both!) you want lombok to generate. #3950.val and @ExtensionMethod could sometimes cause erroneous errors (in that you see errors but compilation succeeds anyway) using javac. #3947.@Jacksonized + fields marked transient would result in those transient fields being serialised which is surprising (and thus undesired) behaviour. #3936.