package de.ormtest;

import java.util.List;

import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.OneToMany;
import javax.persistence.OrderColumn;

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Foo {
    private long id;
    private String name;
    private String descr;
    private List<Bar> list;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public long getId() {
	return id;
    }

    public void setId(long id) {
	this.id = id;
    }

    @Basic
    public String getName() {
	return name;
    }

    public void setName(String name) {
	this.name = name;
    }

    @Basic
    public String getDescr() {
	return descr;
    }

    public void setDescr(String descr) {
	this.descr = descr;
    }

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @OrderColumn(name = "JPA_ORDERING")
    public List<Bar> getList() {
	return list;
    }

    public void setList(List<Bar> list) {
	this.list = list;
    }
}

package de.ormtest;

import javax.persistence.Basic;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Bar {
    private long id;
    private String name;
    private String descr = "hallo";

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public long getId() {
	return id;
    }

    public void setId(long id) {
	this.id = id;
    }

    @Basic
    public String getName() {
	return name;
    }

    public void setName(String name) {
	this.name = name;
    }

    @Basic
    public String getDescr() {
	return descr;
    }

    public void setDescr(String descr) {
	this.descr = descr;
    }
}

package de.ormtest;

import java.util.LinkedList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceUnit;

public class Main {
    @PersistenceUnit(unitName = "ormtest")
    private static EntityManagerFactory emf = Persistence
	    .createEntityManagerFactory("ormtest");

    @PersistenceContext(unitName = "ormtest")
    private static EntityManager em = emf.createEntityManager();

    public static void main(String[] args) {
	{
	    Foo foo = new Foo();
	    foo.setName("fooName");
	    List<Bar> bars = new LinkedList<Bar>();
	    for (int j = 0; j < 300; j++) {
		Bar bar = new Bar();
		bar.setName("barName" + j);
		bars.add(bar);
	    }
	    foo.setList(bars);

	    EntityTransaction et = em.getTransaction();
	    et.begin();
	    em.persist(foo);
	    et.commit();
	}

	Foo result = em.find(Foo.class, 1L);
	em.detach(result);
	em.close();

	System.out.println(result);
	// Here I'm getting the wohle list, although the object is detached
	System.out.println(result.getList());
	System.out.println(result.getList().size());
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
	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_1_0.xsd">
	<persistence-unit name="ormtest">
		<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>

		<class>de.ormtest.Foo</class>
		<class>de.ormtest.Bar</class>

		<properties>
			<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
			<!-- ;create=true -->
			<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/ormtest" />

			<property name="javax.persistence.jdbc.user" value="root" />
			<property name="javax.persistence.jdbc.password" value="root" />

			<property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
			<property name="eclipselink.ddl-generation.output-mode"
				value="database" />
			<property name="eclipselink.weaving" value="static" />
		</properties>
	</persistence-unit>
</persistence>