aws-support/src/main/java/com/streamsets/pipeline/lib/aws/s3/S3Accessor.java
AWSCredentialsProvider createCredentialsProvider() throws StageException {
    String accessKey = credentialConfigs.getAccessKey().get();
    String secretKey = credentialConfigs.getSecretKey().get();
    if (accessKey != null && !accessKey.isEmpty() && secretKey != null && !secretKey.isEmpty()) {
      return new AWSStaticCredentialsProvider(new BasicAWSCredentials(credentialConfigs.getAccessKey().get(),
          credentialConfigs.getSecretKey().get()
      ));
    }
    return null;
  }
AWSCredentialsProvider createCredentialsProvider() throws StageException {
    String accessKey = credentialConfigs.getAccessKey().get();
    String secretKey = credentialConfigs.getSecretKey().get();
    if (accessKey != null && !accessKey.isEmpty() && secretKey != null && !secretKey.isEmpty()) {
      return new AWSStaticCredentialsProvider(new BasicAWSCredentials(credentialConfigs.getAccessKey().get(),
          credentialConfigs.getSecretKey().get()
      ));
    }
    return null;
  }
visible for testing