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.metamodel;


Instances of the type CollectionAttribute represent persistent 
java.util.Collection-valued attributes.

Type parameters:
  • <X> – The type the represented Collection belongs to
  • <E> – The element type of the represented Collection
Since:Java Persistence 2.0
/**
 * Instances of the type <code>CollectionAttribute</code> represent persistent 
 * <code>java.util.Collection</code>-valued attributes.
 *
 * @param <X> The type the represented Collection belongs to
 * @param <E> The element type of the represented Collection
 *
 * @since Java Persistence 2.0
 *
 */
public interface CollectionAttribute<X, E> 
	extends PluralAttribute<X, java.util.Collection<E>, E> {}