Use this URL as a working example: http://ci.jenkins-ci.org/view/Jenkins%20core/job/jenkins_main_trunk/1637/api/json

When looking at a specific build for a given job, the JSON produced for the Remote API functionality is invalid when the changeSet is not null. Using the example above, the JSON returned from this api call results in the changeSet object containing two author and msg objects. These duplicate keys are causing errors with external parsers that are downloading data using the api.

Steps to reproduce:
1.) Using the URL above, attempt to validate the JSON using JSLint (www.jslint.com)
2.) You will receive a duplicate 'author' and 'msg' error.
3.) Using a build that does not have a changeSet does not contain the duplicates and therefore produces valid JSON.

https://builds.apache.org/job/ActiveMQ/918/api/json can also be used (Jenkins 1.457) to verify. A duplicate changeSet/items/msg will be found.

Expected result:
1.) Data should validate properly (and therefore parse.)