diff --git a/src/main/php/Lazy/PDepend/DependencyInjection/Configuration.strong.php b/src/main/php/Lazy/PDepend/DependencyInjection/Configuration.strong.php
deleted file mode 100644
index 797feb4..0000000
--- a/src/main/php/Lazy/PDepend/DependencyInjection/Configuration.strong.php
+++ /dev/null
@@ -1,72 +0,0 @@
-<?php
-/**
- * This file is part of PDepend.
- *
- * PHP Version 5
- *
- * Copyright (c) 2008-2017 Manuel Pichler <mapi@pdepend.org>.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- *   * Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer.
- *
- *   * Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in
- *     the documentation and/or other materials provided with the
- *     distribution.
- *
- *   * Neither the name of Manuel Pichler nor the names of his
- *     contributors may be used to endorse or promote products derived
- *     from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- * @copyright 2008-2017 Manuel Pichler. All rights reserved.
- * @license http://www.opensource.org/licenses/bsd-license.php BSD License
- */
-
-namespace PDepend\DependencyInjection;
-
-use Symfony\Component\Config\Definition\Builder\TreeBuilder;
-use Symfony\Component\Config\Definition\ConfigurationInterface;
-
-// <AbstractConfiguration>
-/**
- * This is the class that validates and merges configuration
- *
- * @copyright 2008-2017 Manuel Pichler. All rights reserved.
- * @license http://www.opensource.org/licenses/bsd-license.php BSD License
- *
- * @codeCoverageIgnore
- */
-abstract class AbstractConfiguration implements ConfigurationInterface
-{
-    /**
-     * @var TreeBuilderFactory
-     */
-    protected $treeBuilderFactory;
-
-    /**
-     * {@inheritDoc}
-     */
-    public function getConfigTreeBuilder(): TreeBuilder
-    {
-        return $this->treeBuilderFactory->getConfigTreeBuilder();
-    }
-}
-// </AbstractConfiguration>