Most probably you are testing an API protected by OAuth therefore:

• nonce: is basically a number used once so my expectation is that it is a some form of a timestamp so you should be able to generate one using JMeter's __time() function

• opaque: looking at RFC 6749

  An opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user-agent back to the client.

  so you should get this opaque state value from the previous response.

Check out How to Run Performance Tests on OAuth Secured Apps with JMeter for more information on bypassing OAuth login challenge in JMeter tests.

Most probably you are testing an API protected by OAuth therefore:

• nonce: is basically a number used once so my expectation is that it is a some form of a timestamp so you should be able to generate one using JMeter's __time() function

• opaque: looking at RFC 6749

  An opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user-agent back to the client.

  so you should get this opaque state value from the previous response.

Check out How to Run Performance Tests on OAuth Secured Apps with JMeter for more information on bypassing OAuth login challenge in JMeter tests.