9.18.2 Notes on data source specification
With the data source specification in persistence.xml, you can use the user-specified Namespace functionality, which is an Application Server functionality, to assign an optional name to the resource adapter. If you set an optional name for the resource adapter in the persistence.xml settings, the optional name of the resource adapter must also be defined in the HITACHI Connector Property file. For details, see 9.19 Settings in the execution environment.