* Copyright 2014 dc-square GmbH
* 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
* 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
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Asynchronous callbacks are executed at the same time. Although the execution of the callbacks is asynchronous, most callbacks get synchronized after executing to receive the results.
Don't implement this interface on your own, use a more concrete interface when you want to add a callback