presto-google-sheets/src/main/java/io/prestosql/plugin/google/sheets/SheetsRecordCursor.java/SheetsRecordCursor/advanceNextPosition
class SheetsRecordCursor:    @Override
    public boolean advanceNextPosition()
    {
        List<Object> currentVals = null;
        // Skip empty rows from sheet
        while (currentVals == null || currentVals.size() == 0) {
            if (currentIndex == dataValues.size()) {
                return false;
            }
            currentVals = dataValues.get(currentIndex++);
        }
        // Populate incomplete columns with null
        String[] allFields = new String[columnHandles.size()];

        for (int i = 0; i < allFields.length; i++) {
            int ordinalPos = columnHandles.get(i).getOrdinalPosition();
            if (currentVals.size() > ordinalPos) {
                allFields[i] = String.valueOf(currentVals.get(ordinalPos));
            }
        }
        fields = Arrays.asList(allFields);
        return true;
    }