@javax.jdo.annotation.PrimaryKey annotation is used by JDO/DataNucleus to indicate that a property is used as the primary key for an entity with application-managed identity.
Apache Isis also uses this annotation in a very minimal way: to ensure that the framework’s own logic to initialize newly instantiated objects (eg using FactoryService#create(…) does not touch the primary key, and also to ensure that the primary key property is always disabled (read-only).
Apache Isis parses the
Moreover, while JDO/DataNucleus will recognize annotations on either the field or the getter method, Apache Isis (currently) only inspects the getter method. Therefore ensure that the annotation is placed there.