    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
    015    package org.apache.tapestry5.ioc.annotations;
    016
    017    import java.lang.annotation.Documented;
    018    import java.lang.annotation.Retention;
    019    import java.lang.annotation.Target;
    020
    021    import static java.lang.annotation.ElementType.METHOD;
    022    import 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)
    035    public @interface Optional
    036    {
    037    }