Created the NotFoundHandler to handle messages that could not be replied (for example not finished listeners)

src/main/java/de/gnmyt/autoresponder/handler/NotFoundHandler.java

@@ -0,0 +1,16 @@
+package de.gnmyt.autoresponder.handler;
+
+import java.util.List;
+
+public abstract class NotFoundHandler {
+
+    /**
+     * Handles the specific request whenever the message could not be found
+     *
+     * @param sender  The sender of the message / the creator of the request
+     * @param message The message that the author sent
+     * @return the list of messages that you want to reply
+     */
+    public abstract List<String> handleRequest(String sender, String message);
+
+}