001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.ioc.annotations;
016
017import java.lang.annotation.Documented;
018import java.lang.annotation.Retention;
019import java.lang.annotation.Target;
020
021import static java.lang.annotation.ElementType.METHOD;
022import static java.lang.annotation.RetentionPolicy.RUNTIME;
023
024/**
025 * Marks a service contribution method within a module as being optional: it is not an error if the contribution does not match against an actual service. In that case, the
026 * method will simply never be invoked.
027 *
028 * @see Contribute
029 * @since 5.3
030 */
031@Target(METHOD)
032@Retention(RUNTIME)
033@Documented
034@UseWith(AnnotationUseContext.MODULE)
035public @interface Optional
036{
037}