The `activeNames`doesn't work well.

[messi-gao]

https://sortablejs.github.io/Vue.Draggable/#/third-party

The activeNames default value is [1],so I think the first data [Consistency] should be in open state,but actually it is in close state.

I try to modify activeNames value,but it doesn't work.unless you click the Element collapse firstly,then the inputChanged mothod will invoke,and at this time,if I modify activeNames value,it can work well.