Meantime, here is some text from the specification making it clear that certain modifiers are not required to be supported.
6.2 All class and field modifiers supported by the Java language including A6.2-1 [private], A6.2-2 [public], A6.2-3 [protected], A6.2-4 [static], A6.2-5 [transient], A6.2-6 [abstract], A6.2-7 [final], A6.2-8 [synchronized], and A6.2-9 [volatile], should be supported by JDO instances. There are some known issues with final and static field, therefore implementations are not required to support making final or static fields persistent.
6.4.4 Static and final fields
Static fields pose a challenge for implementations. Since they are singletons typically initialized when the class is loaded, there is no convenient time to load the values from the database. Therefore, static fields are not persistent.
Final fields pose a challenge for implementations. While it is possible to modify the values of static fields, it can only be done via reflection and there are synchronization issues. Therefore, final fields are not persistent.
6.4.5 Complex enum types
Complex enum types are enums that contain fields that might change during execution instead of being initialized at class initialization. While it is possible to manage these singleton instances persistent state, there are issues with the transaction isolation of the instances and with the ownership of the instances by a persistence manager. Therefore, dynamically changing fields of enum types are not persistent.