compartment has hardcoded constant property (for sbml validation)

converter-sbml/src/main/java/lcsb/mapviewer/converter/model/sbml/compartment/SbmlCompartmentExporter.java

@@ -24,10 +24,15 @@ public class SbmlCompartmentExporter extends SbmlElementExporter<Compartment, or
 
   @Override
   public org.sbml.jsbml.Compartment createSbmlElement(Compartment element) throws InconsistentModelException {
+    org.sbml.jsbml.Compartment result;
     if (element == null || element.getElementId().equals("default")) {
-      return getSbmlModel().createCompartment("default");
+      result = getSbmlModel().createCompartment("default");
+    } else {
+      result = getSbmlModel().createCompartment("comp_" + (getNextId()));
     }
-    return getSbmlModel().createCompartment("comp_" + (getNextId()));
+    //for now we don't have this information - needed for validation
+    result.setConstant(true);
+    return result;
   }
 
   @Override