Add license header.

src/main/java/com/github/mfl28/boundingboxeditor/controller/KeyCombinations.java

@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2024 Markus Fleischhacker <markus.fleischhacker28@gmail.com>
+ *
+ * This file is part of Bounding Box Editor
+ *
+ * Bounding Box Editor is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Bounding Box Editor is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Bounding Box Editor. If not, see <http://www.gnu.org/licenses/>.
+ */
 package com.github.mfl28.boundingboxeditor.controller;
 
 import javafx.scene.input.KeyCode;