code: public Map<String, Map<String, SubsystemConfig>> getSubsystemConfigs(File featurePackFile) throws IOException, XMLStreamException {
          Map<String, Map<String, SubsystemConfig>> subsystems = new HashMap<>();
          try (ZipFile zip = new ZipFile(featurePackFile)) {
              ZipEntry zipEntry = zip.getEntry(getSubsystems());
              if (zipEntry == null) {
                  throw new RuntimeException("Feature pack " + featurePackFile + " subsystems file " + getSubsystems() + " not found");
              }
              InputStreamSource inputStreamSource = new ZipEntryInputStreamSource(featurePackFile, zipEntry);
              SubsystemsParser.parse(inputStreamSource, getProperties(), subsystems);
          }
          return subsystems;
      }
docs: Retrieves the subsystems configs.
  @param featurePackFile the feature pack's file containing the subsystem configs
  @return
  @throws IOException
  @throws XMLStreamException