TestFromClientSideWithCoprocessor - This was a bug in the test itself, PR runs missed it somehow.
TestCustomSaslAuthenticationProvider - This was written pre master registry. Has to be updated. It was never run as a part of the test suite.
TestSnapshotScannerHDFSAclController: Cluster restart did not reset the cached connection state
ndimiduk FYI because this is a blocker for 2.3.0 too, I tagged it accordingly. Will submit a PR shortly.