#fixed code
                              @Override
  public Collection<String> getAllTypeNames()
  {
    FqnCache<LocklessLazyVar<M>> fqnCache = _fqnToModel.get();
    if( fqnCache.isEmpty() )
    {
      return Collections.emptySet();
    }

    return fqnCache.getFqns();
  }
#vulnerable code 
                              @Override
  public Collection<String> getAllTypeNames()
  {
    return _fqnToModel.get().getFqns();
  } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE