WebLogic Server has been providing both OpenJPA/Kodo and EclipseLink as JPA providers since WLS 10.3.1.
Unless an explicit <provider>...</provider> is specifed in the persistence.xml file of a deployed application, WLS will use OpenJPA/Kodo by default.
With the release of WLS 10.3.3, we have now provided a way to change the default JPA provider at the domain level, allowing you to switch between OpenJPA/Kodo or EclipseLink as the default that WLS will use.
The default JPA provider setting is exposed via a new MBean: JPAMBean on the DomainMBean, and persists the configuration into the config.xml file.
To easiest way to change the default JPA provider it to use the console and select the desired provider value.