using the following injection:

@PersistenceContext(unitName = "myUnit", properties = { @PersistenceProperty(name = "mykey" value = "myvalue") })
 

the properties attribute wont be processed by the WeldJpaInjectionServices, so the values wont be passed to the underlying vendor specific entitymanager later.

In the following line: https://github.com/wildfly/wildfly/blob/802969514ae18ba21c2cda389d59f54eca3ccb3a/weld/jpa/src/main/java/org/jboss/as/weld/services/bootstrap/WeldJpaInjectionServices.java#L142

the TransactionScopedEntityManager will be constructed with an empty hashmap instead of the persistencecontext.properties() ( context variable )