co.elastic.apm.api.HeaderExtractor Maven / Gradle / Ivy
/*
* Licensed to Elasticsearch B.V. under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch B.V. licenses this file to you 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
*
* http://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 co.elastic.apm.api;
/**
* Used to extract the first header with a specific header name.
*
* Can be implemented as a lambda in Java 8 and as an anonymous inner class in Java 7.
*
*/
public interface HeaderExtractor {
/**
* Returns the value of the provided header name
*
* @param headerName the name of the header to extract
* @return the value of the provided header name
*/
String getFirstHeader(String headerName);
}