@JsonProperty("s3")
        public S3 getS3() {
            return s3;
        }
JSON wrapper of an {@link S3Link} identifier,
which consists of the S3 region id, bucket name and key.
Sample JSON serialized form:
<pre>
{"s3":{"bucket":"mybucket","key":"mykey","region":"us-west-2"}}
{"s3":{"bucket":"mybucket","key":"mykey","region":null}}
</pre>
Note for S3 a null region means US standard.
<p>
 @see Region#US_Standard
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/S3Link.java