--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/flowdepth/FlowDepthPairSelectState.java	Tue Mar 13 09:55:53 2018 +0100
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/flowdepth/FlowDepthPairSelectState.java	Tue Mar 13 18:49:33 2018 +0100
@@ -1,6 +1,6 @@
 /** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
- * Software engineering by 
- *  Björnsen Beratende Ingenieure GmbH 
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
  *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
  *
  * This file is Free Software under the GNU AGPL (>=v3)
@@ -15,13 +15,15 @@
  * @author Gernot Belger
  *
  */
-public class FlowDepthPairSelectState
-// FIXME: very ugly; but probably we will break the serialization of WaterlevelPairSelectState if we introduce an abstraction 
-extends WaterlevelPairSelectState {
+// FIXME: very ugly; but probably we will break the serialization of WaterlevelPairSelectState if we introduce an
+// abstraction
+public final class FlowDepthPairSelectState extends WaterlevelPairSelectState {
+
+    private static final long serialVersionUID = 1L;
 
     /** Specify to display a datacage_twin_panel. */
     @Override
     protected String getUIProvider() {
         return "sinfo_flowdepth_twin_panel";
     }
-}
+}
\ No newline at end of file