issues that were discovered during biohackathon 2019 in Paris

converter/src/main/java/lcsb/mapviewer/converter/ZIndexPopulator.java

@@ -37,8 +37,6 @@ public class ZIndexPopulator {
    * @param model
    */
   public void populateZIndex(Model model) {
-    int maxZIndex = 0;
-
     List<Drawable> bioEntities = new ArrayList<>();
     for (Layer layer : model.getLayers()) {
       bioEntities.addAll(layer.getOvals());
@@ -46,7 +44,15 @@ public class ZIndexPopulator {
       bioEntities.addAll(layer.getTexts());
     }
     bioEntities.addAll(model.getBioEntities());
-    bioEntities.sort(new Comparator<Drawable>() {
+    
+    populateZIndex(bioEntities);
+
+  }
+
+  public void populateZIndex(Collection<? extends Drawable> drawables) {
+    List<? extends Drawable> sortedDrawables=new ArrayList<>(drawables);
+    int maxZIndex = 0;
+    sortedDrawables.sort(new Comparator<Drawable>() {
       @Override
       public int compare(Drawable o1, Drawable o2) {
         if (o1 instanceof Reaction) {
@@ -91,11 +97,10 @@ public class ZIndexPopulator {
       }
     });
 
-    for (Drawable bioEntity : bioEntities) {
+    for (Drawable bioEntity : sortedDrawables) {
       if (bioEntity.getZ() == null) {
         bioEntity.setZ(++maxZIndex);
       }
     }
-
   }
 }