@Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD}) 
@Retention(RetentionPolicy.RUNTIME)
public @interface Unique
{
    /** Name of the unique constraint.
     * @return the name of the unique constraint
     */
    String name() default "";

    /** Table for the unique constraint. This is needed iff annotating a type 
     * where this unique constraint is not for the primary table for 
     * the persistent class or interface.
     * @return the table on which the unique constraint is defined
     */
    String table() default "";

    /** Whether this unique constraint is deferred until commit.
     * @return whether this unique constraint is deferred until commit
     */
    String deferred() default "";

    /** Member (field and property) names that compose this unique constraint.
     * @return member names that compose this unique constraint
     */
    String[] members() default {};

    /** Columns that compose this unique constraint.
     * @return columns that compose this unique constraint
     */
    Column[] columns() default {};
}