...

Response Variables:{X-Frame-Options=SAMEORIGIN, Status=200, X-AR-TR-Core-Id=uhR8-xO5iY1g, X-AR-TR-Counter=1, X-Content-Type-Options=nosniff, Content-Security-Policy=frame-ancestors 'self', Content-Length=0, X-XSS-Protection=1; mode=block, Date=Mon, 13 Dec 2021 11:38:37 GMT, Location=http://remedy-api-instance/api/arsys/v1/entry/SYSCOM:VendorTransmission/000000000022038}

Get the INV Request number using Groovy: name it {{INCREQ_NUM}}

def urlToInc = scope.responseHeaders.Location
def parts = urlToInc.split("/")
return parts[parts.length-1]

Update the issue

1. Click Create

2. Select Action and enter a name

3. Select Template Category: Jira Core Server

4. Select Template: Edit Issue 

5. Click Create

6. In the configuration select a authentication user to use when updating the Jira issue (Basic Auth)

7. In the body section paste the code in below and change the customfield id to match your field.

{
    "fields":{"customfield_10201":"{{REQ_NUM}}"}
}

Reference https://community.bmc.com/s/article/How-to-create-a-Service-Request-through-REST-API