Unable to modify the value Product Number on Start and End Submit via script

Summary

Unable to modify the value Product Number on Start and End Submit in the Order Management Extension screen

Content

Hello all,

I have the below script which supposedly lets the system update the value of the field "Allow Partial Shipments of Lines" to No among another field.

def SDetails = header.getAttribute("Lines");                
while( SDetails.hasNext() ) { 
def line = SDetails.next();                              
def itemNumber = line.getAttribute("ProductNumber");
def PartialShipFlag = line.setAttribute("HeaderPartialShipAllowedFlag", "No");
def AutoDefine = line.setAttribute("ShipSetName", itemNumber);

The error generated is this:

“JBO-DOO:::DOO_CX_INVALID_UPDATE: <MESSAGE><NUMBER>DOO-2685897</NUMBER><TEXT>The extension Order-Extension cannot update attribute ShipSetName, of entity Line, during event On End of Submission Request, because this attribute is read-only.</TEXT><CAUSE></CAUSE><ACTION></ACTION><DETAILS></DETAILS><INCIDENT></INCIDENT></MESSAGE>”