Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
    Linda DeMichiel - Java Persistence 2.1
    Linda DeMichiel - Java Persistence 2.0
/*******************************************************************************
 * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.1
 *     Linda DeMichiel - Java Persistence 2.0
 *
 ******************************************************************************/ 
package javax.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.ConstraintMode.PROVIDER_DEFAULT;

Groups PrimaryKeyJoinColumn annotations. It is used to map composite foreign keys. 
   Example: ValuedCustomer subclass
   @Entity
   @Table(name="VCUST")
   @DiscriminatorValue("VCUST")
   @PrimaryKeyJoinColumns({
       @PrimaryKeyJoinColumn(name="CUST_ID", 
           referencedColumnName="ID"),
       @PrimaryKeyJoinColumn(name="CUST_TYPE",
           referencedColumnName="TYPE")
   })
   public class ValuedCustomer extends Customer { ... }

See Also:
ForeignKey
Since:
Java Persistence 1.0/**
 * Groups {@link PrimaryKeyJoinColumn} annotations.
 * It is used to map composite foreign keys.
 *
 * <pre>
 *    Example: ValuedCustomer subclass
 *
 *    &#064;Entity
 *    &#064;Table(name="VCUST")
 *    &#064;DiscriminatorValue("VCUST")
 *    &#064;PrimaryKeyJoinColumns({
 *        &#064;PrimaryKeyJoinColumn(name="CUST_ID", 
 *            referencedColumnName="ID"),
 *        &#064;PrimaryKeyJoinColumn(name="CUST_TYPE",
 *            referencedColumnName="TYPE")
 *    })
 *    public class ValuedCustomer extends Customer { ... }
 * </pre>
 *
 * @see ForeignKey
 *
 * @since Java Persistence 1.0
 */
@Target({TYPE, METHOD, FIELD})
@Retention(RUNTIME)

public @interface PrimaryKeyJoinColumns {

    
One or more PrimaryKeyJoinColumn annotations. /** One or more <code>PrimaryKeyJoinColumn</code> annotations. */
    PrimaryKeyJoinColumn[] value();

    
 (Optional) Used to specify or control the generation of a
 foreign key constraint when table generation is in effect. 
 If both this element and the foreignKey element 
 of any of the PrimaryKeyJoinColumn elements are specified, 
 the behavior is undefined.  If no foreign key annotation element
 is specified in either location, the persistence provider's
 default foreign key strategy will apply.
 @since Java Persistence 2.1
/**
     *  (Optional) Used to specify or control the generation of a
     *  foreign key constraint when table generation is in effect. 
     *  If both this element and the <code>foreignKey</code> element 
     *  of any of the <code>PrimaryKeyJoinColumn</code> elements are specified, 
     *  the behavior is undefined.  If no foreign key annotation element
     *  is specified in either location, the persistence provider's
     *  default foreign key strategy will apply.
     *
     *  @since Java Persistence 2.1
     */
    ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);

}