fixed parent calculation in connection

org.fortiss.tooling.base.ui/trunk/src/org/fortiss/tooling/base/ui/editpart/command/ConnectCommand.java

@@ -33,7 +33,7 @@ import org.fortiss.tooling.kernel.service.IConnectionCompositorService;
  * @author hoelzl
  * @author $Author$
  * @version $Rev$
- * @ConQAT.Rating GREEN Hash: 19A76A681820E49F4E8397BA1AB5358E
+ * @ConQAT.Rating YELLOW Hash: 56AD20144F81EC2E610E4B0DAFE7FCDE
  */
 public class ConnectCommand extends Command {
 
@@ -59,9 +59,13 @@ public class ConnectCommand extends Command {
 		if(context.getSource().getModel() instanceof EObject &&
 				context.getTarget().getModel() instanceof EObject &&
 				context.getSource().getParent().getModel() instanceof EObject) {
+			EObject commonParent = getCommonParent();
+			if(commonParent == null) {
+				return false;
+			}
 			return IConnectionCompositorService.INSTANCE.canConnect((EObject)context.getSource()
-					.getModel(), (EObject)context.getTarget().getModel(), (EObject)context
-					.getSource().getParent().getModel(), context);
+					.getModel(), (EObject)context.getTarget().getModel(), getCommonParent(),
+					context);
 		}
 		return false;
 	}
@@ -69,12 +73,20 @@ public class ConnectCommand extends Command {
 	/** {@inheritDoc} */
 	@Override
 	public void execute() {
-		EObject sourceParent = (EObject)context.getSource().getParent().getModel();
-		EObject targetParent = (EObject)context.getTarget().getParent().getModel();
-
-		EObject commonParent = findCommonParent(sourceParent, targetParent);
 		IConnectionCompositorService.INSTANCE.connect((EObject)context.getSource().getModel(),
-				(EObject)context.getTarget().getModel(), commonParent, context);
+				(EObject)context.getTarget().getModel(), getCommonParent(), context);
+	}
+
+	/** Returns the common parent. */
+	private EObject getCommonParent() {
+		Object srcEObject = context.getSource().getParent().getModel();
+		Object targetEObject = context.getTarget().getParent().getModel();
+		if(!(srcEObject instanceof EObject && targetEObject instanceof EObject)) {
+			return null;
+		}
+		EObject sourceParent = (EObject)srcEObject;
+		EObject targetParent = (EObject)targetEObject;
+		return findCommonParent(sourceParent, targetParent);
 	}
 
 	/** Finds the common parent of two elements. */