private static SolrInputDocument toSolr(DcsCollection col, ArchiveStore store)
      throws IOException {
    SolrInputDocument doc = new SolrInputDocument();

    add(doc, EntityField.ID, col.getId());
    add(doc, EntityField.TYPE, EntityTypeValue.COLLECTION.solrValue());

    if (col.getParent() != null) {
      add(doc, CollectionField.PARENT, col.getParent().getRef());
    }

    add(doc, CoreMetadataField.TITLE, col.getTitle());

    addMetadataSet(doc, col.getMetadata());
    addMetadataRefSet(doc, col.getMetadataRef(), EntityField.METADATA_REF, store);

    addResourceIdentifierSet(doc, col.getAlternateIds());

    add(doc, CoreMetadataField.TYPE, col.getType());

    addStrings(doc, col.getSubjects(), CoreMetadataField.SUBJECT);
    // addStrings(doc, col.getCreators(), CoreMetadataField.CREATOR);
    //        addCreatorSet(doc,col.getCreators());

    return doc;
  }