private void appendShapeInternal(StringBuilder sb) {
		if (type == ShapeType.RECTANGLE && shield > 0) {
			throw new UnsupportedOperationException();
		} else if (type == ShapeType.RECTANGLE) {
			sb.append("shape=rect");
		} else if (type == ShapeType.DIAMOND) {
			sb.append("shape=diamond");
		} else if (type == ShapeType.CIRCLE) {
			sb.append("shape=circle");
		} else if (type == ShapeType.CIRCLE_IN_RECT) {
			sb.append("shape=circle");
		} else if (type == ShapeType.OVAL) {
			sb.append("shape=ellipse");
		} else if (type == ShapeType.ROUND_RECTANGLE) {
			sb.append("shape=rect,style=rounded");
		} else {
			throw new IllegalStateException(type.toString());
		}
	}