https://github.com/javaee/jpa-spec: Java(TM) Persistence API 
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.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.ConstraintMode.PROVIDER_DEFAULT;


Specifies the mapping for composite foreign keys. This annotation 
groups JoinColumn annotations for the same relationship.

 When the JoinColumns annotation is used, 
both the name and the referencedColumnName elements 
must be specified in each such JoinColumn annotation.

   Example:
   @ManyToOne
   @JoinColumns({
       @JoinColumn(name="ADDR_ID", referencedColumnName="ID"),
       @JoinColumn(name="ADDR_ZIP", referencedColumnName="ZIP")
   })
   public Address getAddress() { return address; }



See Also:
Since:Java Persistence 1.0
/**
 * Specifies the mapping for composite foreign keys. This annotation 
 * groups <code>JoinColumn</code> annotations for the same relationship.
 *
 * <p> When the <code>JoinColumns</code> annotation is used, 
 * both the <code>name</code> and the <code>referencedColumnName</code> elements 
 * must be specified in each such <code>JoinColumn</code> annotation.
 *
 * <pre>
 *
 *    Example:
 *    &#064;ManyToOne
 *    &#064;JoinColumns({
 *        &#064;JoinColumn(name="ADDR_ID", referencedColumnName="ID"),
 *        &#064;JoinColumn(name="ADDR_ZIP", referencedColumnName="ZIP")
 *    })
 *    public Address getAddress() { return address; }
 * </pre>
 *
 * @see JoinColumn
 * @see ForeignKey
 *
 * @since Java Persistence 1.0
 */
@Target({METHOD, FIELD}) 
@Retention(RUNTIME)
public @interface JoinColumns {

    
The join columns that map the relationship.

/**
     * The join columns that map the relationship.
     */
    JoinColumn[] 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 JoinColumn 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>JoinColumn</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);
}