001    /**
002     * Copyright 2005-2012 The Kuali Foundation
003     *
004     * Licensed under the Educational Community License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.opensource.org/licenses/ecl2.php
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    package org.kuali.rice.kew.api.identity;
017    
018    import java.io.Serializable;
019    
020    /**
021     * Superinterface of UserId and GroupId
022     * @author Kuali Rice Team (rice.collab@kuali.org)
023     */
024    public interface Id extends Serializable {
025        /**
026         * Returns true if this Id has an empty value. Empty Ids can't be used as keys in a Hash,
027         * among other things.
028         *
029         * @return true if this instance doesn't have a value
030         */
031        public boolean isEmpty();
032    }