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/*
 * Copyright (c) 2008, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Linda DeMichiel - 2.1
//     Linda DeMichiel - 2.0

package jakarta.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;

/**
 * Applied to a persistent field or property of an entity 
 * class or mapped superclass to denote a composite primary 
 * key that is an embeddable class. The embeddable class 
 * must be annotated as {@link Embeddable}. 
 *
 * 

There must be only one EmbeddedId annotation and * no Id annotation when the EmbeddedId annotation is used. * *

The {@link AttributeOverride} annotation may be used to override * the column mappings declared within the embeddable class. * *

The {@link MapsId} annotation may be used in conjunction * with the EmbeddedId annotation to specify a derived * primary key. * *

If the entity has a derived primary key, the * AttributeOverride annotation may only be used to * override those attributes of the embedded id that do not correspond * to the relationship to the parent entity. * *

Relationship mappings defined within an embedded id class are not supported. * *

 *    Example 1:
 *
 *    @EmbeddedId
 *    protected EmployeePK empPK;
 *
 *
 *    Example 2:
 *
 *    @Embeddable
 *    public class DependentId {
 *       String name;
 *       EmployeeId empPK;   // corresponds to primary key type of Employee
 *    }
 *
 *    @Entity
 *    public class Dependent {
 *       // default column name for "name" attribute is overridden
 *       @AttributeOverride(name="name", @Column(name="dep_name"))
 *       @EmbeddedId DependentId id;
 *       ...
 *       @MapsId("empPK")
 *       @ManyToOne Employee emp;
 *    }
 * 
* * @see Embeddable * @see MapsId * * @since 1.0 */ @Target({METHOD, FIELD}) @Retention(RUNTIME) public @interface EmbeddedId {}




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