currently a record can only be an IdentityObject but at some point, we want to introduce an inline record ?
Indeed so.
Now the question: What the subtyping relation between java.lang.Record and InlineObject/IdentityObject ? An identity record (resp. an inline record) should be a subtype of both java.lang.Record and IdentityObject (resp InlineObject). Given that java.lang.Record has to be an abstract class because you can not re-abstract an interface method. So both IdentityObject and InlineObject are interface and java.lang.Record inherits from Object. Am i right ? Or do we really care about re-abstracting the methods of j.l.Record ?
This is right. j.l.Record will be one of those "inline-friendly abstract classes", which can be a superclass for either identity or inline records. (Enum will not be, as it has fields.)