Use Java EE 7 Default Datasource in persistence.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
  <persistence-unit name="forge-default" transaction-type="JTA">
    <description>Forge Persistence Unit</description>
    <jta-data-source>java:jboss/datasources/ExampleDS</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
      <property name="javax.persistence.schema-generation.scripts.action" value="drop-and-create"/>
      <property name="javax.persistence.schema-generation.scripts.create-target" value="pluralsight-persistenceCreate.ddl"/>
      <property name="javax.persistence.schema-generation.scripts.drop-target" value="pluralsight-persistenceDrop.ddl"/>
    </properties>
  </persistence-unit>
</persistence>