@Override
    public void shutdown() {
        super.shutdown();
        if (isKMSClientInternal)
            kms.shutdown();
    }
{@inheritDoc}
<p>
If the a default internal KMS client has been constructed, it will also be
shut down by calling this method.
Otherwise, users who provided the KMS client would be responsible to
shut down the KMS client extrinsic to this method.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/AmazonS3EncryptionClient.java