001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    
018    package org.apache.logging.log4j.core.config.plugins.validation.constraints;
019    
020    import java.lang.annotation.Documented;
021    import java.lang.annotation.ElementType;
022    import java.lang.annotation.Retention;
023    import java.lang.annotation.RetentionPolicy;
024    import java.lang.annotation.Target;
025    
026    import org.apache.logging.log4j.core.config.plugins.validation.Constraint;
027    import org.apache.logging.log4j.core.config.plugins.validation.validators.RequiredValidator;
028    
029    /**
030     * Marks a plugin builder field or plugin factory parameter as required.
031     *
032     * @since 2.1
033     */
034    @Documented
035    @Retention(RetentionPolicy.RUNTIME)
036    @Target({ElementType.FIELD, ElementType.PARAMETER})
037    @Constraint(RequiredValidator.class)
038    public @interface Required {
039    
040        /**
041         * The message to be logged if this constraint is violated. This should normally be overridden.
042         */
043        String message() default "The parameter is null";
044    }