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
018package org.apache.logging.log4j.core.config.plugins.validation.constraints;
019
020import java.lang.annotation.Documented;
021import java.lang.annotation.ElementType;
022import java.lang.annotation.Retention;
023import java.lang.annotation.RetentionPolicy;
024import java.lang.annotation.Target;
025
026import org.apache.logging.log4j.core.config.plugins.validation.Constraint;
027import 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)
038public @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}