When SFT runs, it installs components based on unpatched version of standard-features.xml, which means it has down-revved aries-proxy (1.1.3 vs. 1.1.4) – thus failing on interface default methods.
It also seems test-distribution boot features are based on unpatched versions as well.
This leads to us testing not what we are shipping, but rather against vanilla karaf-4.2.2.
We need to fix this, as we are forced to deploy workarounds for https://issues.apache.org/jira/browse/ARIES-1923 in at least three components.