Corey, I'm really sorry for the churn. I thought I ran both forward and backward compatibility modes last time (-old 1.6.1 -new 1.6.2 as well as -old 1.6.2 -new 1.6.1), but I must have just eyeballed the output of the 1.6.1 -> 1.6.2 report for problems with forward compatibility.
I ran things again this time (as a formality) and the 1.6.2 -> 1.6.1 check turned up 2 issues.
1) minicluster.ServerType added enum members
Specifically TRACER and MONITOR. This changes the public API because ServerType is in it, and a client built against 1.6.2 could refer to these enum values and then get a NoSuchFieldError if they try to go back to 1.6.1. This only shows up as a low severity "other" issue in the 1.6.1 -> 1.6.2 check, which is probably why I didn't see it.
2) core.client.mapreduce.AbstractInputFormat.getConfiguration(JobContext) changed from package-private to public
This causes the method to show up as a new part of the public API. This issue only shows up in the 1.6.2 -> 1.6.1 check below.
Here are the specific report outputs for others to look:
* 1.6.0 -> 1.6.2 (added things are fine, because the change might be from 1.6.0 -> 1.6.1)
* 1.6.1 -> 1.6.2 (nothing should be added, but it's easier to just pay attention to the next one)
* 1.6.2 -> 1.6.1 (under a semver patch increment, this should be just as strong an assertion as the reverse)