Awesome, thanks for jumping on this so quickly!

cc @comius

cc @lberki

Since both @ahumesky and @comius were tagged into this code review and they didn't respond, I hereby declare it to be Good Enough To Be Merged.

@bazel-io flag

@bazel-io fork 6.4.0

@fmeum @ahumesky @lberki @ismell There were some conflicts when cherry-picking this to release-6.4.0.

1. src/main/java/com/google/devtools/build/lib/analysis/OutputGroupInfo.java

for (OutputGroupInfo provider : providers) {
  for (String outputGroup : provider.outputGroups.keySet()) {
    if (!seenGroups.add(outputGroup)) {
      throw new DuplicateException(
          "Output group " + outputGroup + " provided twice");
    }

    resultBuilder.put(outputGroup, provider.getOutputGroup(outputGroup));
  }
}

is in release-6.4.0 branch. But expected below before the cherry-pick

for (OutputGroupInfo provider : providers) {
  for (String group : provider) {
    if (outputGroups.put(group, provider.getOutputGroup(group)) != null) {
      throw new DuplicateException("Output group " + group + " provided twice");
    }
  }
}

Also, return new OutputGroupInfo(resultBuilder.buildOrThrow()); is in release-6.4.0 branch currently, which was not expected before the cherry-pick.

cc: @bazelbuild/triage

@iancha1992 I performed a manual cherry-pick in #19745.

Thanks!