[eclipse] Copyright header

[MoritzKeppler]

We need to include a copyright header in every source file, see
https://www.eclipse.org/projects/handbook/#ip-copyright-headers

/********************************************************************************
 * Copyright (c) {year} {owner}[ and others] 
 *
 * This program and the accompanying materials are made available under the 
 * terms of the Apache License, Version 2.0 which is available at
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * SPDX-License-Identifier: Apache-2.0
 * 
 * Contributors: 4
 *   {name} - {description}
 ********************************************************************************/