...

• The changes are 100% API compatible with current version
• All new properties and added arguments to APIs are optional 
• To enable the feature, users can store the broker to rack mapping information in their own ways, implement the RackLocator interface and pass in the additional configuration for broker or command line tools.

Rejected Alternatives

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.