EntityManager jak wyłączyć encje z automatycznego tworzenia tabel?

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
			 xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
			 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
	<persistence-unit name="Eclipselink_JPA"
					  transaction-type="RESOURCE_LOCAL">
<class>org.entites.Message_Header</class>
		<class>org.entites.Message_Info</class>
		<class>org.entites.Message_Parameters</class>
<shared-cache-mode>DISABLE_SELECTIVE</shared-cache-mode>
		<properties>
			<property name="javax.persistence.query.timeout" value="1000" />
		</properties>
	</persistence-unit>
</persistence>

properties.put("eclipselink.ddl-generation", "create-or-extend-tables");
    	properties.put("javax.persistence.query.timeout", "1000");