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;


This annotation must be specified for persistent map keys of type Date and Calendar. It may only be specified for map keys of these types. 
 The MapKeyTemporal annotation can be applied to an
element collection or relationship of type java.util.Map
in conjunction with the ElementCollection,
OneToMany, or ManyToMany annotation.

    Example:
    @OneToMany
    @MapKeyTemporal(DATE)
    protected java.util.Map<java.util.Date, Employee> employees;



Since:Java Persistence 2.0
/**
 * This annotation must be specified for persistent map keys of type 
 * {@link java.util.Date} and {@link java.util.Calendar}. It may only be 
 * specified for map keys of these types.
 * 
 * <p> The <code>MapKeyTemporal</code> annotation can be applied to an
 * element collection or relationship of type <code>java.util.Map</code>
 * in conjunction with the <code>ElementCollection</code>,
 * <code>OneToMany</code>, or <code>ManyToMany</code> annotation.
 *
 * <pre>
 *     Example:
 * 
 *     &#064;OneToMany
 *     &#064;MapKeyTemporal(DATE)
 *     protected java.util.Map&#060;java.util.Date, Employee&#062; employees;
 * </pre>
 *
 * @since Java Persistence 2.0
 */
@Target({METHOD, FIELD}) 
@Retention(RUNTIME)
public @interface MapKeyTemporal {

    
(Required) The type used in mapping
java.util.Date or
java.util.Calendar. 

/** (Required) The type used in mapping
     * <code>java.util.Date</code> or
     * <code>java.util.Calendar</code>. 
     */
    TemporalType value();
}