export a formula with an external reference incorrectly

Steps to Reproduce

1. visit the zul
2. click the button to export
3. import the exported file back
4. check A1:A4

Current Result

the cells A1:A4 don't show the expected values from source.xlsx A1:A4

Expected Result

shows the expected values from source.xlsx A1:A4

Debug Information

• the original formula is =[source.xlsx]Input!A1, after exporting it becomes =Input!A1