PackageSet addPackages(List<String> packageNames) {
            var newPackages = packageNames.stream()
                    .map(p -> new PackageInfo(p, "", List.of()))
                    .toList();
            return new PackageSet(new ArrayList<>(packages) {{ addAll(newPackages); }});
        }
Integration tests for {@link ExportPackages}.

@author gjoranv
jdisc_core/src/test/java/com/yahoo/jdisc/core/ExportPackagesIT.java