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/*
 * Copyright (C) 2009 The JSR-330 Expert Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jakarta.inject;

import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

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

/**
 * Identifies qualifier annotations. Anyone can define a new qualifier. A qualifier annotation:
 *
 * 
 *   is annotated with {@code @Qualifier}, {@code @Retention(RUNTIME)}, and typically
 *       {@code @Documented}.
 *   
can have attributes.
 *   
may be part of the public API, much like the dependency type, but unlike implementation
 *       types which needn't be part of the public API.
 *   
may have restricted usage if annotated with {@code @Target}. While this specification
 *       covers applying qualifiers to fields and parameters only, some injector configurations
 *       might use qualifier annotations in other places (on methods or classes for example).
 * 
 *
 * For example:
 *
 * 
 *   @java.lang.annotation.Documented
 *   @java.lang.annotation.Retention(RUNTIME)
 *   @jakarta.inject.Qualifier
 *   public @interface Leather {
 *     Color color() default Color.TAN;
 *     public enum Color { RED, BLACK, TAN }
 *   }
 *
 * @see jakarta.inject.Named @Named
 */
@Target(ANNOTATION_TYPE)
@Retention(RUNTIME)
@Documented
public @interface Qualifier {}