Been working with Mick on CI and it dawned on me that we don't specify a specific required JDK version (major.minor.patch) for CI nor do we actually specify required python lib versions for many of the requirements in our dtests <https://github.com/apache/cassandra-dtest/blob/trunk/requirements.txt>. We might implicitly enforce those via coordination between circle and the ASF env currently, but "Repeatable ci-cassandra.a.o" in CASSANDRA-18137 <https://issues.apache.org/jira/browse/CASSANDRA-18137> opens this up to being a potential drift point for tests.
So my questions: 1. Does anyone protest the idea of "If you run CI in your own environment <https://issues.apache.org/jira/browse/CASSANDRA-18137> to validate a commit, here's the specific JDK version you need to use"? 2. Anyone concerned about us being specific about versions in requirements.txt in the dtest repo?
