I have created sandbox using https://go.docusign.com/o/sandbox/ and able to generate integrator key and private/public key.
I have downloded https://github.com/docusign/eg-01-java-jwt code and configure key as per given instruction.
It's giving me error like "com.docusign.esign.client.ApiException: Error while requesting an access token: POST https://account-d.docusign.com/oauth/token returned a response status of 400 Bad Request"