ST6RI-850 Added protective null pointer check in TransitionUsageAdapter.

Checks if TransitionUsage succession is null before creating an implicit
binding connector to it. A TransitionUsage should always have a
nested succession, but this avoids an NPE if the usage is ill-formed.

Author: seidewitz

org.omg.sysml/src/org/omg/sysml/adapter/TransitionUsageAdapter.java

@@ -94,10 +94,12 @@ protected Feature computeTransitionLinkConnectors() {
 		Feature transitionLinkFeature = UsageUtil.getTransitionLinkFeatureOf(transition);
 		if (transitionLinkFeature == null) {
 			// checkTransitionUsageSuccessionBindingConnector
-			transitionLinkFeature = SysMLFactory.eINSTANCE.createReferenceUsage();
-			TypeUtil.addOwnedFeatureTo(transition, transitionLinkFeature);			
 			Succession succession = transition.getSuccession();
-			addBindingConnector(succession, transitionLinkFeature);		
+			if (succession != null) {
+				transitionLinkFeature = SysMLFactory.eINSTANCE.createReferenceUsage();
+				TypeUtil.addOwnedFeatureTo(transition, transitionLinkFeature);			
+				addBindingConnector(succession, transitionLinkFeature);
+			}
 
 			// checkTransitionUsageSourceBindingConnector
 			List<Feature> parameters = TypeUtil.getOwnedParametersOf(transition);