public void generateOfflineDiskStores(Set<PersistentID> offLineDiskStores) {
    String[] diskStores = new String[offLineDiskStores.size()];
    offLineDiskStores.stream().map(PersistentID::getDirectory).collect(Collectors.toList())
        .toArray(diskStores);
    setOfflineDiskStores(diskStores);
  }
Sets the list of directories for the disk stores that were off-line at the time the backup
occurred.
geode-core/src/main/java/org/apache/geode/management/internal/DiskBackupStatusImpl.java