public static Workbook openWorkbook(File excelFile) throws ETLException {
        try {
            return WorkbookFactory.create(excelFile);
        } catch (IOException | InvalidFormatException e) {
            ETLInterfaceLogger.getLogger().error("Cannot open Excel file");
            throw new ETLException("Error opening excel file: " + e.getMessage());
        }
    }

public void writeWorkbook(File outputPath) throws ETLException {
        FileOutputStream stream = null;
        try {
            stream = new FileOutputStream(outputPath);
            workbook.write(stream);
            stream.close();
            workbook.close();
        } catch (IOException e) {
            throw new ETLException("Error writing XLSX to disk: " + e.getMessage());
        } finally {
            if (stream != null)
                try {
                    stream.close();
                } catch (IOException e) {
                    ETLInterfaceLogger.getLogger().error("Cannot close outputstream: " + e.getMessage());
                }
        }
    }