How to get transaction Id while confirming the authentication

https://dev.abdm.gov.in/gateway/v0.5/users/auth/fetch-modes
https://dev.abdm.gov.in/gateway/v0.5/users/auth/init
received status code 202 accepted and OTP as authCode from above URL’s subsequent posting but not received an transaction id from below URL that needs to pass through body.
https://dev.abdm.gov.in/gateway/v0.5/users/auth/confirm
Need to pass transaction Id while posting above URL.
body response given below
{“requestId”:“5f7a535d-a3fd-416b-b069-c97d021fbacd”,“timestamp”:“2022-04-16T06:07:38.754Z”,“transactionId”:“string”,“credential”:{“authCode”:“877660”,“demographic”:{“name”:“rajesh bhattacharya”,“gender”:“M”,“dateOfBirth”:“1972-03-15”,“identifier”:{“type”:“MOBILE”,“value”:"+919876543210"}}}}
How to get that transaction id?