how to skip 1 st line of payload - groovy - groovy

Question

I have final payload in csv format with some amount of employee records. I have 2 main values to work with:
-Sequence field (added for each record)
-personal_id (unique for every employee)
Because of the fact that each employee can have multiple records, the need is to have according sequence number for each ID. In other words If employee with ID "123" have 5 records, the sequence value should be 1,2,3,4,5 instead of 1,1,1,1,1. All records are grouped by ID.
Also the payload below shows only 2 fields needed for the description, normally it has much more fields and is an example of static payload. Normally it will be dynamically.
here are the input payload:
Sequence;ID
123456
232323
232323
232323
111111
111111
222222
222222
222222
222222
222222
222222
222222
and here is expected payload
Sequence;ID
1;123456
1;232323
2;232323
3;232323
1;111111
2;111111
1;222222
2;222222
3;222222
4;222222
5;222222
6;222222
7;222222
Here is the actual payload after using groovy script:
1;Sequence;ID
1;123456
1;232323
2;232323
3;232323
1;111111
2;111111
1;222222
2;222222
3;222222
4;222222
5;222222
6;222222
7;222222
I am using the following groovy script but the problem is that the first line of payload is also numbered by 1. Can you show me how to skip the first line of payload?
The script is adding a number in every record to have it counted. The clue is to have all records of the same id counted from 1 incrementally. The script does that perfectly but the issue is as I said while i want to skip the first line od payload "Sequence;..." to not have it counted.
import com.sap.gateway.ip.core.customdev.util.Message
def Message processData(Message message) {
def payload = message.getBody(java.lang.String)
def prevId = ''
def sequence = 1
def sb = new StringBuilder()
def line = new StringReader()
payload.eachLine { line ->
def values = line.split(';')
if (values[1] != prevId) {
// New personal ID
sequence = 1
prevId = values[1]
} else {
// Another line of the same personal ID
sequence += 1
}
line = readLine()
values[0] = sequence
sb.append(values.join(';')).append(System.lineSeparator())
}
message.setBody(sb.toString())
return message
}

Answer 1

Assuming message is just a String, .eachLine can be given two arguments: the line and the index. You could use that to do whatever logic you want in your closure: skip index 0 entirely, output it as-is, etc.
Basic example:
payload.eachLine { line, idx ->
if (idx == 0) {
// do something with the first line
} else {
// everything you currently have
}
}