#fixed code
                              @Override
  public void assign(RingGroup ringGroup, int ringNum, Domain domain) throws IOException {
    ring = ringGroup.getRing(ringNum);
    domainGroup = ringGroup.getDomainGroup();
    domainId = domainGroup.getDomainId(domain.getName());
    version = domainGroup.getLatestVersion().getVersionNumber();
    random = new Random();

    for (Integer partNum : ring.getUnassignedPartitions(domain)) {
      getMinHostDomain().addPartition(partNum, version);
    }

    while (!isDone()) {
      HostDomain maxHostDomain = getMaxHostDomain();
      HostDomain minHostDomain = getMinHostDomain();

      ArrayList<HostDomainPartition> partitions = new ArrayList<HostDomainPartition>();
      partitions.addAll(maxHostDomain.getPartitions());
      int partNum = partitions.get(random.nextInt(partitions.size())).getPartNum();

      HostDomainPartition partition = maxHostDomain.getPartitionByNumber(partNum);
      try {
        if (partition.getCurrentDomainGroupVersion() == null)
          partition.delete();
        else
          partition.setDeletable(true);
      } catch (Exception e) {
        partition.setDeletable(true);
      }

      minHostDomain.addPartition(partNum, version);
    }
  }
#vulnerable code 
                              @Override
  public void assign(RingGroup ringGroup, int ringNum, Domain domain) throws IOException {
    ring = ringGroup.getRing(ringNum);
    domainGroup = ringGroup.getDomainGroup();
    domainId = domainGroup.getDomainId(domain.getName());
    version = domainGroup.getLatestVersion().getVersionNumber();
    random = new Random();

    for (Integer partNum : ring.getUnassignedPartitions(domain)) {
      HostDomain minHostDomain = getMinHostDomain();
      minHostDomain.addPartition(partNum, version);
    }

    while (!isDone()) {
      HostDomain maxHostDomain = getMaxHostDomain();
      HostDomain minHostDomain = getMinHostDomain();

      ArrayList<HostDomainPartition> partitions = new ArrayList<HostDomainPartition>();
      partitions.addAll(maxHostDomain.getPartitions());
      int partNum = partitions.get(random.nextInt(partitions.size())).getPartNum();

      HostDomainPartition partition = maxHostDomain.getPartitionByNumber(partNum);
      try {
        if (partition.getCurrentDomainGroupVersion() == null)
          partition.delete();
        else
          partition.setDeletable(true);
      } catch (Exception e) {
        partition.setDeletable(true);
      }

      minHostDomain.addPartition(partNum, version);
    }
  } 
                            #location 11 
                            #vulnerability type NULL_DEREFERENCE