Add Java-Kompendium book

Java-Kompendium/kap3/HalloWelt.java

@@ -0,0 +1,11 @@
+// OOP sucks.
+public class HalloWelt {
+    /**
+     * Java sucks.
+     *
+     * @param args Command line arguments.
+     */
+    public static void main(String[] args) {
+        System.out.print("Java sucks\n");
+    }
+}