basic toString method implemented

model/src/main/java/lcsb/mapviewer/model/map/reaction/ReactionNode.java

@@ -5,6 +5,7 @@ import javax.persistence.Entity;
 import javax.persistence.ManyToOne;
 
 import lcsb.mapviewer.model.map.species.Element;
+import lcsb.mapviewer.modelutils.map.ElementUtils;
 
 /**
  * One of two known types of nodes in the {@link Reaction}. It defines input or
@@ -91,5 +92,10 @@ public abstract class ReactionNode extends AbstractNode {
   public void setStoichiometry(Double stoichiometry) {
     this.stoichiometry = stoichiometry;
   }
+  
+  @Override
+  public String toString() {
+    return new ElementUtils().getElementTag(this);
+  }
 
 }