onValidation.js

import("system.vars");
import("system.result");
import("system.neon");
import("Order_lib");
import("Entity_lib");

if(vars.get("$sys.recordstate") == neon.OPERATINGSTATE_NEW
    && !OrderUtils.validateOrderNumber(ProcessHandlingUtils.getOnValidationValue(vars.get("$field.SALESORDERCODE"))))
{
    vars.set("$field.SALESORDERCODE", OrderUtils.getNextOrderNumber().toString());
}