DocuSign JWT access toke call fails in Dev environment while successful in Local - jwt

Question

We are trying to integrate with DocuSign, and using JWT authorization in Spring Boot application.
When I am running my application locally (running in local Tomcat) I am able to connect to DocuSign and email documents successfully. However, once I deployed the code to our Development environment (running Websphere), the call to request JWT token is returning below Exception. Keep in mind I am using the same base URL and Integrator key in both environments:
Exception: Error while requesting server, received a non successful HTTP code 401 with response Body: '{
"errorCode": "PARTNER_AUTHENTICATION_FAILED",
"message": "The specified Integrator Key was not found or is disabled. An Integrator key was not specified."
}'
Call to request JWT token:
ApiClient apiClient = new ApiClient(BASE_URL);
apiClient.configureJWTAuthorizationFlow(currentDir + PUBLIC_KEY_FILENAME, currentDir + PRIVATE_KEY_FILENAME, OAUTH_BASE_URL, INTEGRATOR_KEY, USER_ID, expireIn);
BASE_URL = https://demo.docusign.net/restapi
OAUTH_BASE_URL = account-d.docusign.com
I have values set for the rest of the variables as well; I'm just showing variable names only here.
I have already granted access by making the following call and logging in the browser by making the following call in a test class:
String oauthLoginUrl = apiClient.getJWTUri(INTEGRATOR_KEY, REDIRECT_URI, OAUTH_BASE_URL);
Desktop.getDesktop().browse(URI.create(oauthLoginUrl));
I'd appreciate any help. Thank you.

Answer 1

After days of trying out different things finally resolved my issue, posting the answer here in case it helps someone else.
In my dev env even though file name was loaded correctly apiClient could not load the correct file, and in local tomcat server that was not the case. After seeing the same exception when I changed the fileName in for local server, made a guess that server is failing to read the correct key files.
Instead of passing the file name directly I had to use Thread.currentThread().getContextClassLoader().getResource(publicKeyFileName).getPath(); for both public and private keys and that resolved the issue.