Use external repository mirrors in build (#6094) We've been bitten by external repository fluctuation for a long time. This PR makes most of tests use repository mirrors set up by ourselves via init script and system property.
There're still some tests not switching to mirrors, which would be fixed in follow-up commits.
Expose deprecation warning messages and stacktraces via build operations (#5881) Expose deprecation warnings as operation progress events
- introduce split of message, warning and advice - make deprecation progress events immutable - rework deprecation handling/messages to support more a richer model - update build operation progress model - tweak existing deprecation warnings to match new model - Add performance test + make stacktrace calculation for build ops lazy - Always include a trace with FeatureUsage now that its always required