<persistence passivation="false">
   <!-- note that class is missing and is induced by the fileStore element name -->
   <file-store
           shared="false" preload="true"
           fetch-state="true"
           read-only="false"
           purge="false"
           path="${java.io.tmpdir}">
      <write-behind thread-pool-size="5" />
   </file-store>
</persistence>
