On the hdfs dev list, they are talking about EOL Hadoop 2.10 (and thus 2.x). They may cherry-pick back critical CVE fixes but not create any more releases. Of course, the decision is not final yet, but I wonder if we should make a similar decision for supporting 2.10 in hbase.
Given that 2.6 is soon, we could mark the end of support in that release. While it may seem like a major change, there is some precedent for this. Looking at our compatibility matrix, we have dropped support for Hadoop releases in minor releases in the past. Dropping support for Hadoop 2 in HBase 2.6 would allow us to start cleaning up our POMs and some of the hacks we've had to do to reflect around Hadoop releases. It may also free up Jenkins capacity since we can turn off some builds for our primary branches.
