Issue #54 - Fixed possible NPE in getEffectiveParameters.

Author: seidewitz

org.modeldriven.alf/dist/alf-base.jar

@@ -24,7 +24,7 @@
 
 public abstract class AlfBase {
 
-    public static final String ALF_VERSION = "1.1.0a";
+    public static final String ALF_VERSION = "1.1.0a/maint-3";
 
     protected boolean isVerbose = false;
 

org.modeldriven.alf/src/org/modeldriven/alf/execution/AlfBase.java

@@ -175,8 +175,11 @@ public List<ElementReference> getEffectiveParameters() {
         } else {
             List<ElementReference> parameters = new ArrayList<ElementReference>();
             if (this.isReception()){
-                for (ElementReference property: this.getSignal().getImpl().getAttributes()) {
-                    parameters.add(parameterFromProperty(property).getImpl().getReferent());
+                ElementReference signal = this.getSignal();
+                if (signal != null) {
+                    for (ElementReference property: signal.getImpl().getAttributes()) {
+                        parameters.add(parameterFromProperty(property).getImpl().getReferent());
+                    }
                 }
             } else if (this.isDataType() || this.isSignal()){
                 for (ElementReference property: this.getAttributes()) {