Just kicked off a build of the Streams system tests (e.g., TC_PATHS=tests/kafkatest/tests/streams/streams_upgrade_test.py) using this PR:
https://jenkins.confluent.io/job/system-test-kafka-branch-builder/4082/

and a full system test run using this PR: https://jenkins.confluent.io/job/system-test-kafka-branch-builder/4083/

Thanks, @mjsax

The streams-only system test run (https://jenkins.confluent.io/job/system-test-kafka-branch-builder/4082/) passed. The other was interrupted by a Jenkins restart. I'll restart the full system test run tomorrow AM.

Green builds on JDK 11 and 14, and two unrelated failures (known flaky integration tests, not system tests) on JDK 8:

Test Result (2 failures / +1)
    org.apache.kafka.streams.integration.EosBetaUpgradeIntegrationTest.shouldUpgradeFromEosAlphaToEosBeta[false]
    org.apache.kafka.streams.integration.EosBetaUpgradeIntegrationTest.shouldUpgradeFromEosAlphaToEosBeta[true]

I started a second run of all system tests with this branch: https://jenkins.confluent.io/job/system-test-kafka-branch-builder/4088/

The [second run|https://jenkins.confluent.io/job/system-test-kafka-branch-builder/4088] with all of the system tests had [two failures|http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2020-08-04--001.1596577078--rhauch--kafka-10341--f0164cbb3/report.html]:

Module: kafkatest.tests.core.round_trip_fault_test 
Class:  RoundTripFaultTest 
Method: test_round_trip_workload_with_broker_partition

Module: kafkatest.tests.client.consumer_test
Class:  OffsetValidationTest
Method: test_static_consumer_bounce 
Arguments: {   "bounce_mode": "all",   "clean_shutdown": true,   "num_bounces": 5,   "static_membership": false }

These have been somewhat flaky recently on the 2.6 branch (at least), but they are not directly affected by this PR.