org.eclipse.core.runtime.AssertionFailedException: null argument: Business object com.brsanthu.rfe.sfdcobjectmodel.impl.SfdcObjectImpl@12231e35 (name: Test) is not contained in a resource

    @Override
    public PictogramElement add(IAddContext context) {
        SfdcObject object = (SfdcObject) context.getNewObject();
        Diagram targetDiagram = (Diagram) context.getTargetContainer();

        // CONTAINER SHAPE WITH ROUNDED RECTANGLE
        IPeCreateService peCreateService = Graphiti.getPeCreateService();
        ContainerShape containerShape =
             peCreateService.createContainerShape(targetDiagram, true);

        // define a default size for the shape
        int width = 100;
        int height = 50;
        IGaService gaService = Graphiti.getGaService();

        {
            // create and set graphics algorithm
            RoundedRectangle roundedRectangle =
                gaService.createRoundedRectangle(containerShape, 5, 5);
            roundedRectangle.setForeground(manageColor(CLASS_FOREGROUND));
            roundedRectangle.setBackground(manageColor(CLASS_BACKGROUND));
            roundedRectangle.setLineWidth(2);
            gaService.setLocationAndSize(roundedRectangle,
                context.getX(), context.getY(), width, height);

            // create link and wire it
            link(containerShape, object);
        }

        // SHAPE WITH LINE
        {
            // create shape for line
            Shape shape = peCreateService.createShape(containerShape, false);

            // create and set graphics algorithm
            Polyline polyline =
                gaService.createPolyline(shape, new int[] { 0, 20, width, 20 });
            polyline.setForeground(manageColor(CLASS_FOREGROUND));
            polyline.setLineWidth(2);
        }

        // SHAPE WITH TEXT
        {
            // create shape for text
            Shape shape = peCreateService.createShape(containerShape, false);

            // create and set text graphics algorithm
            Text text = gaService.createDefaultText(getDiagram(), shape, object.getName());
            text.setForeground(manageColor(CLASS_TEXT_FOREGROUND));
            text.setHorizontalAlignment(Orientation.ALIGNMENT_CENTER);
            text.setVerticalAlignment(Orientation.ALIGNMENT_CENTER);
            text.getFont().setBold(true);
            gaService.setLocationAndSize(text, 0, 0, width, 20);

            // create link and wire it
            link(shape, object);
        }

        return containerShape;
    }