Jdbc persistence does not start (missing javax.transaction.xa)

I have just installed a clean build # 576 of OpenHab2 on a Rasperry Pi 3 with Oracle JDK 1.8u111, and am trying to set up persistence with a postgresql database.

I have added the postgresql.jar to …/addons directory as documented in the wiki. Immediately on startup of the OH2 server, I get the following exception:

2016-11-08 18:59:11.302 [WARN ] [org.apache.felix.fileinstall        ] - Error while starting bundle: file:/home/openhab/2.0.0-576/addons/postgresql-9.4.1209.jre7.jar
org.osgi.framework.BundleException: Could not resolve module: org.postgresql.jdbc41     [10]
  Unresolved requirement: Import-Package: javax.transaction.xa
        at org.eclipse.osgi.container.Module.start(Module.java:434)[org.eclipse.osgi-3.10.2.v20150203-1939.jar:]
        at org.eclipse.osgi.internal.framework.EquinoxBundle.start(EquinoxBundle.java:393)[org.eclipse.osgi-3.10.2.v20150203-1939.jar:]
        at org.apache.felix.fileinstall.internal.DirectoryWatcher.startBundle(DirectoryWatcher.java:1245)[8:org.apache.felix.fileinstall:3.5.0]

The interesting part seems to be the

  Unresolved requirement: Import-Package: javax.transaction.xa

Any idea what I can do to fix this?

The driver seems to do something, though: It decides that the driver is available:

2016-11-08 19:22:34.029 [INFO ] [persistence.jdbc.internal.JdbcMapper] - JDBC::openConnection: Driver is available::Yank setupDataSource

and manages to create a table “items” with an sequence in my otherwise empty schema:

openhab=# \d
               List of relations
 Schema |       Name       |   Type   |  Owner
 public | items            | table    | openhab
 public | items_itemid_seq | sequence | openhab
(2 rows)