hortonworks
CB-18776: Added new StackV4 method which retrieves backup data sizes after they have been collected.
Jira: https://jira.cloudera.com/browse/CB-18776
Please look at this section in my design document to understand the overall idea behind this work.
The overall objective of this is to enable external services to actually retrieve the result of the flow from #13550, this being via the stack status reason which is updated at the end of that flow.
The primary work in here is therefore just adding a simple service which interprets the JSON string in the stack status reason and transforms it into a full response.
This has been tested by creating a local DL, running the entire flow from #13550, and then using the exposed endpoint in this change (via Postman 2) to obtain the response object with all of the fields being verified.
Labeling this as DO NOT MERGE as this depends on changes in #13550 and #13549.