Steps to Reproduce

1. run the zul
2. click the button to change the model
It replaces a model having one series of TOTAL_AMOUNT1

Current Result

the legend of TOTAL_AMOUNT2 still exists

Expected Result

the legend of TOTAL_AMOUNT2 doesn't exist because there is no data for it

Debug Information

• chart.setModel(new DefaultCategoryModel()) doesn't clear the legends, either.

Workaround

call model.clear() before setting a new model