proper operator type is used for heterodimer association

model-command/src/main/java/lcsb/mapviewer/commands/layout/ApplySimpleLayoutModelCommand.java

@@ -25,11 +25,14 @@ import lcsb.mapviewer.model.map.compartment.Compartment;
 import lcsb.mapviewer.model.map.model.Model;
 import lcsb.mapviewer.model.map.reaction.AbstractNode;
 import lcsb.mapviewer.model.map.reaction.AndOperator;
+import lcsb.mapviewer.model.map.reaction.AssociationOperator;
 import lcsb.mapviewer.model.map.reaction.Modifier;
+import lcsb.mapviewer.model.map.reaction.NodeOperator;
 import lcsb.mapviewer.model.map.reaction.Product;
 import lcsb.mapviewer.model.map.reaction.Reactant;
 import lcsb.mapviewer.model.map.reaction.Reaction;
 import lcsb.mapviewer.model.map.reaction.SplitOperator;
+import lcsb.mapviewer.model.map.reaction.type.HeterodimerAssociationReaction;
 import lcsb.mapviewer.model.map.species.Complex;
 import lcsb.mapviewer.model.map.species.Element;
 import lcsb.mapviewer.model.map.species.Species;
@@ -240,9 +243,13 @@ public class ApplySimpleLayoutModelCommand extends ApplyLayoutModelCommand {
   }
 
   private void modifyReactants(Reaction reaction, Point2D middle) {
-    AndOperator operator = null;
+    NodeOperator operator = null;
     if (reaction.getReactants().size() > 1) {
-      operator = new AndOperator();
+      if (reaction instanceof HeterodimerAssociationReaction) {
+        operator = new AssociationOperator();
+      } else {
+        operator = new AndOperator();
+      }
       Point2D productPoint = reaction.getReactants().get(0).getElement().getCenter();
       Point2D operatorPoint = getMiddlePoint(middle, productPoint);
       operator.setLine(new PolylineData(middle, operatorPoint));