001    // =================================================================================================
002    // Copyright 2011 Twitter, Inc.
003    // -------------------------------------------------------------------------------------------------
004    // Licensed under the Apache License, Version 2.0 (the "License");
005    // you may not use this work except in compliance with the License.
006    // You may obtain a copy of the License in the LICENSE file, or at:
007    //
008    //  http://www.apache.org/licenses/LICENSE-2.0
009    //
010    // Unless required by applicable law or agreed to in writing, software
011    // distributed under the License is distributed on an "AS IS" BASIS,
012    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013    // See the License for the specific language governing permissions and
014    // limitations under the License.
015    // =================================================================================================
016    
017    package com.twitter.common.args.constraints;
018    
019    import java.lang.annotation.Retention;
020    import java.lang.annotation.Target;
021    
022    import static java.lang.annotation.ElementType.FIELD;
023    import static java.lang.annotation.RetentionPolicy.RUNTIME;
024    
025    /**
026     * Annotation that indicates an entity must exist.
027     *
028     * @author William Farner
029     */
030    @Target(FIELD)
031    @Retention(RUNTIME)
032    public @interface Exists {
033    }