docs: private static Optional<FieldDiffs> copyFieldDiffOfIssueFromOtherBranch(String issueKey, FieldDiffs c) {
      FieldDiffs result = new FieldDiffs();
      result.setIssueKey(issueKey);
      result.setUserUuid(c.userUuid());
      result.setCreationDate(c.creationDate());
      // Don't copy "file" changelogs as they refer to file uuids that might later be purged
      c.diffs().entrySet().stream().filter(e -> !e.getKey().equals(IssueFieldsSetter.FILE))
        .forEach(e -> result.setDiff(e.getKey(), e.getValue().oldValue(), e.getValue().newValue()));
      if (result.diffs().isEmpty()) {
        return Optional.empty();
      }
      return Optional.of(result);
    }