j2ee.persistence/test/unit/data/persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence">
  <persistence-unit name="em" transaction-type="JTA">
    <jta-data-source>jdbc/__default</jta-data-source>
    <properties>
      <property name="ddl-generation" value="createtables"/>
    </properties>
  </persistence-unit>
  <persistence-unit name="em2" transaction-type="JTA">
    <jta-data-source>jdbc/__default</jta-data-source>
    <properties>
      <property name="ddl-generation" value="createtables"/>
    </properties>
  </persistence-unit>
</persistence>