public String getETag() {
        return eTag;
    }
Returns the entity tag identifying the new object. An entity tag is an
opaque string that changes if and only if an object's data changes.

@return An opaque string that changes if and only if an object's data
        changes.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/transfer/model/UploadResult.java