Add missing license header

Signed-off-by: David Schwilk <david.schwilk@bosch.io>

base/service/src/main/java/org/eclipse/ditto/base/service/DittoExtensionPoint.java

@@ -1,3 +1,15 @@
+/*
+ * Copyright (c) 2022 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package org.eclipse.ditto.base.service;
 
 import java.util.List;