/*
 * Copyright 2014-2022 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.integration.annotation;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Provides the message header {@code value} or {@code expression}.
 *
 * @author Artem Bilan
 * @since 4.0
 */
@Target({})
@Retention(RetentionPolicy.RUNTIME)
public @interface GatewayHeader {

	/**
	 * @return The name of the header.
	 */
	String name();

	/**
	 * @return The value for the header.
	 */
	String value() default "";

	/**
	 * @return The {@code Expression} to be evaluated to produce a value for the header.
	 */
	String expression() default "";

}
