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package javax.persistence;

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.EnumType.ORDINAL;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * Specifies the enum type for a map key whose basic type is an enumerated type.
 * 
 * The MapKeyEnumerated annotation can be applied to an element collection or relationship of type java.util.Map,
 * in conjunction with the ElementCollection, OneToMany, or ManyToMany annotation. If the enumerated
 * type is not specified or the MapKeyEnumerated annotation is not used, the enumerated type is assumed to be
 * ORDINAL.
 * 
 *  *   Example:
 * 
 *   public enum ProjectStatus {COMPLETE, DELAYED, CANCELLED, IN_PROGRESS}
 * 
 *   public enum SalaryRate {JUNIOR, SENIOR, MANAGER, EXECUTIVE}
 * 
 *   @Entity public class Employee {
 *       @ManyToMany
 *       public Projects<ProjectStatus, Project> getProjects() {...}
 * 
 *       @OneToMany
 *       @MapKeyEnumerated(STRING)
 *       public Map<SalaryRate, Employee> getEmployees() {...}
 *       ...
 *   }
 * 
 * 
 * @see ElementCollection
 * @see OneToMany
 * @see ManyToMany
 * 
 * @since Java Persistence 2.0
 */
@Target({ METHOD, FIELD })
@Retention(RUNTIME)
public @interface MapKeyEnumerated {

	/** (Optional) The type used in mapping a map key enum type. */
	EnumType value() default ORDINAL;
}