private void validateConnection(Stage.Context context, List<Stage.ConfigIssue> issues) {
   // Access Key ID - username [unique in aws]
   // secret access key - password
   AWSCredentials credentials = new BasicAWSCredentials(accessKeyId, secretAccessKey);
   s3Client = new AmazonS3Client(credentials, new ClientConfiguration());
   s3Client.setS3ClientOptions(new S3ClientOptions().withPathStyleAccess(true));
   if (endPoint != null && !endPoint.isEmpty()) {
     s3Client.setEndpoint(endPoint);
   } else {
     s3Client.setRegion(Region.getRegion(region));
   }
   try {
     // check if the credentials are right by trying to list buckets
     s3Client.listBuckets();
   } catch (AmazonS3Exception e) {
     issues.add(
         context.createConfigIssue(
             Groups.S3.name(), "accessKeyId", Errors.S3_SPOOLDIR_20, e.toString()));
   }
 }