diff --git a/AlgebraicDataflowArchitectureModel/src/simulator/Resource.java b/AlgebraicDataflowArchitectureModel/src/simulator/Resource.java
index f3bd6d9..c221ec0 100644
--- a/AlgebraicDataflowArchitectureModel/src/simulator/Resource.java
+++ b/AlgebraicDataflowArchitectureModel/src/simulator/Resource.java
@@ -20,10 +20,12 @@
 	
 	public Resource(ResourceHierarchy resourceHierarchy) {
 		this.resourceHierarchy = resourceHierarchy;
-		if (resourceHierarchy.getChildren().size() > 0) {
-			ResourceHierarchy childRes = resourceHierarchy.getChildren().iterator().next();
-			if (childRes.getNumParameters() > 0) {
-				Type resType = resourceHierarchy.getResourceStateType();
+		Type resType = resourceHierarchy.getResourceStateType();
+		if (resourceHierarchy.getChildren().size() > 0 
+				|| DataConstraintModel.typeList.isAncestorOf(resType)
+				|| DataConstraintModel.typeMap.isAncestorOf(resType)
+				|| DataConstraintModel.typeJson.isAncestorOf(resType)) {
+			if (resourceHierarchy.getChildren().size() <= 1) {
 				if (DataConstraintModel.typeList.isAncestorOf(resType)) {
 					// List resource
 					state = new ListResourceState();
@@ -36,7 +38,7 @@
 				state = new JsonResourceState();
 				children = new ArrayList<>();
 				for (ResourceHierarchy child: resourceHierarchy.getChildren()) {
-					Resource cRes = new Resource(child);
+					Resource cRes = new Resource(child, this);
 					((JsonResourceState) state).addChildState(child.getResourceName(), cRes.getState());
 					children.add(cRes);
 				}
@@ -46,6 +48,11 @@
 		}
 	}
 	
+	public Resource(ResourceHierarchy resourceHierarchy, Resource parent) {
+		this(resourceHierarchy);
+		this.parent = parent;
+	}
+	
 	public Resource(ResourceHierarchy resourceHierarchy, Resource parent, ResourceState state) {
 		this.resourceHierarchy = resourceHierarchy;
 		this.parent = parent;
diff --git a/AlgebraicDataflowArchitectureModel/src/simulator/states/PrimitiveResourceState.java b/AlgebraicDataflowArchitectureModel/src/simulator/states/PrimitiveResourceState.java
index 6ad1362..d5aba63 100644
--- a/AlgebraicDataflowArchitectureModel/src/simulator/states/PrimitiveResourceState.java
+++ b/AlgebraicDataflowArchitectureModel/src/simulator/states/PrimitiveResourceState.java
@@ -1,6 +1,7 @@
 package simulator.states;
 
 import models.algebra.Constant;
+import models.dataConstraintModel.DataConstraintModel;
 
 public class PrimitiveResourceState extends ResourceState {
 	private Constant value;
@@ -11,6 +12,7 @@
 	
 	@Override
 	public Constant getValue() {
+		if (value == null) return new Constant(DataConstraintModel.null_);
 		return value;
 	}