jpa-customid/src/main/resources/META-INF/orm.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm" version="1.0">
    <entity name="Invoice" class="org.superbiz.nullrelation.Invoice">
        <table name="INVOICE"/>
        <id-class class="org.superbiz.nullrelation.InvoiceKey"/>
        <attributes>
            <id name="id">
                <column name="ID"/>
            </id>
            <id name="brandName">
                <column name="BRANDNAME"/>
            </id>
            <basic name="price">
                <column name="PRICE"/>
            </basic>
            <one-to-many name="lineItems" mapped-by="invoice">
                <cascade>
                    <cascade-all/>
                </cascade>
            </one-to-many>
        </attributes>
    </entity>
    <entity name="LineItemBean" class="org.superbiz.nullrelation.LineItem">
        <table name="ITEM"/>
        <attributes>
            <id name="id">
                <column name="ID"/>
            </id>
            <basic name="quantity">
                <column name="QUANTITY"/>
            </basic>
            <many-to-one name="invoice">
                <join-column referenced-column-name="ID" name="FK_FOR_ID"/>
                <join-column referenced-column-name="BRANDNAME" name="FK_FOR_BRANDNAME"/>
            </many-to-one>
        </attributes>
    </entity>
</entity-mappings>