OCR ExecutionContext error in ThreadPool

I am trying to run the OCR operation in a ThreadPool. My code looks like this:

ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);
executor.submit(() -> {
       Credentials credentials = Credentials.serviceAccountCredentialsBuilder()
                    .fromFile("/home/darvasr/dc-services-sdk-credentials.json")
                    .build();

      ExecutionContext executionContext = ExecutionContext.create(credentials);
      OCROperation ocrOperation = OCROperation.createNew();

But when the ExecutionContext instance gets created the run fails and exception occurs when the AuthenticatorFactory calls this:

return new JwtAuthenticator((ServiceAccountCredentials) credentials);

Detailed exception:

What could be the problem (Same happens when I run it without the ThreadPoolExecutor) ? The OCR-ing works in a separate project.