public static <T> List<CloseableReference<T>> cloneOrNull(
      @PropagatesNullable Collection<CloseableReference<T>> refs) {
    if (refs == null) {
      return null;
    }
    List<CloseableReference<T>> ret = new ArrayList<>(refs.size());
    for (CloseableReference<T> ref : refs) {
      ret.add(CloseableReference.cloneOrNull(ref));
    }
    return ret;
  }
Clones a collection of references and returns a list. Returns null if the list is null. If the
list is non-null, clones each reference. If a reference cannot be cloned due to already being
closed, the list will contain a null value in its place.

@param refs the references to clone
@return the list of cloned references or null
fbcore/src/main/java/com/facebook/common/references/CloseableReference.java