Based on the provided code snippets, I suspect that the code is executed within an event handler. Can you specify in which event exactly?
If the code is executed in the ExcelExport event handler, then the Maximum call stack exceeded exception would be thrown. This is due to the fact that the saveAsExcel method would call the ExcelExport event, therefore, infinite loop is created.
What I can recommend is to do the modifications within the handler of the ExcelExport event. It would not be needed to explicitly call the saveAsExcel() method, and the changes would be present. Also, is it possible for you to check right after the filter method is the rows are changed. If not, then the initial collection would be exported.
Ideally, it would be great if you can isolate the faulty behavior in a sample runnable project and send it back to me. This way, I would have the opportunity to examine the case locally and get back to you with suggestions.
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