Steps to Reproduce

Run attached sample
ExportComposer.java keikai-chart-export.zul
create new workbook
add any chart (bar chart for example) to the sheet
click excel export button
open downloaded file in excel

Current Result

exported title value is ="Title"

Expected Result

exported title is Title

Debug Information

See comment

Workaround

replace ExcelXlsxExporter.java with attached override class