Apollo is distributed under Apache v2.0 license.
http://www.apache.org/licenses/
To apply the Apollo Apache License, attach the following boilerplate notice:

/**
* Copyright 2021 Department of Computer Science, University of Innsbruck
* 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.
*/