private Cell createCellIfNecessary(Row row, Integer lastColumnIndex,
        CellWriteHandlerContext cellWriteHandlerContext) {
        Cell cell = row.getCell(lastColumnIndex);
        if (cell != null) {
            return cell;
        }
        WriteHandlerUtils.beforeCellCreate(cellWriteHandlerContext);
        cell = row.createCell(lastColumnIndex);
        cellWriteHandlerContext.setCell(cell);

        WriteHandlerUtils.afterCellCreate(cellWriteHandlerContext);
        return cell;
    }
The unique data encoding for this fill
fastexcel-core/src/main/java/cn/idev/excel/write/executor/ExcelWriteFillExecutor.java