Delete First Row In Spreadsheet Via Groovy?

Hi,

I need to find someway to automate the update of a unique identifier (see below) contained in my .json post request, so that the submissionid value is automatically incremented by a value of 1 each time the test case executes so that  I can add my ReadyAPI! project into the jenkins pipeline

e.g. json attribute is as below:

"submissionid" : "1234567890123"

I created another post (link) originally cos I was asking about doing it via inline scripting - but I think I've thought of another way of doing it - hence the reason I've created a new post with a more apt title.

If I created a Excel datasource with the values required (e.g. "1111111100000", "1111111100001", "1111111100002".....up to "1111111130000" etc. <--- this would give me more than enough execution runs) and then I had a script that deleted the FIRST row in the spreadsheet (at the end of the test (teardown script)) - then each time the test was executed, the submissionid used in my .json request would be unique.

I've done a bit of reading  there is an 'Apose API' that appears to be reasonably straight forward to delete rows in a spreadsheet, but that looks like it requires money so that's not available.

There is a jxl.jar file that is a sourceforge option for manipulating spreadsheets.....i think this might be the way forward.

I know this is cheeky - cos I'm not coming to you with even an attempt at any code - I just wouldn;t know where to start - I did find the following link which has the following code - but I'm getting nowhere.   

/*
@Author : Pradeep Bishnoi
@Description : Manipulate the data inside an Excel file using jxl api in groovy
@Ref : Thanks to Andy Khan for sharing the reference documents about JXL API.
*/
 
/* code lines first test step*/
 
import jxl.*
import jxl.write.*
WritableWorkbook workbook = Workbook.createWorkbook(new File("d:\\output.xls"))
WritableSheet sheet = workbook.createSheet("Worksheet 1", 0)
log.info(sheet1.isHidden())
Label label = new Label(0, 2, "Test data in Column A, Row 3"); //column=0=A,row=0=1
sheet.addCell(label);
Label label1 = new Label(2, 2, "Column C, Row 3");
sheet.addCell(label1);
workbook.write()
workbook.close()

would anyone know how to delete the FIRST row in a spreadsheet?

Thanks so much guys - I welcome all/any advice anyone can give me!

richie