@Override
 public List<MetadataValue> getMetadata(
     T dso, String schema, String element, String qualifier, String lang, String authority) {
   List<MetadataValue> metadata = getMetadata(dso, schema, element, qualifier, lang);
   List<MetadataValue> result = new ArrayList<>(metadata);
   if (!authority.equals(Item.ANY)) {
     Iterator<MetadataValue> iterator = result.iterator();
     while (iterator.hasNext()) {
       MetadataValue metadataValue = iterator.next();
       if (!authority.equals(metadataValue.getAuthority())) {
         iterator.remove();
       }
     }
   }
   return result;
 }
  @Override
  public void addMetadata(
      Context context,
      T dso,
      MetadataField metadataField,
      String lang,
      List<String> values,
      List<String> authorities,
      List<Integer> confidences)
      throws SQLException {
    boolean authorityControlled = metadataAuthorityService.isAuthorityControlled(metadataField);
    boolean authorityRequired = metadataAuthorityService.isAuthorityRequired(metadataField);

    // We will not verify that they are valid entries in the registry
    // until update() is called.
    for (int i = 0; i < values.size(); i++) {

      MetadataValue metadataValue = metadataValueService.create(context, dso, metadataField);
      metadataValue.setLanguage(lang == null ? null : lang.trim());

      // Logic to set Authority and Confidence:
      //  - normalize an empty string for authority to NULL.
      //  - if authority key is present, use given confidence or NOVALUE if not given
      //  - otherwise, preserve confidence if meaningful value was given since it may document a
      // failed authority lookup
      //  - CF_UNSET signifies no authority nor meaningful confidence.
      //  - it's possible to have empty authority & CF_ACCEPTED if e.g. user deletes authority key
      if (authorityControlled) {
        if (authorities != null && authorities.get(i) != null && authorities.get(i).length() > 0) {
          metadataValue.setAuthority(authorities.get(i));
          metadataValue.setConfidence(
              confidences == null ? Choices.CF_NOVALUE : confidences.get(i));
        } else {
          metadataValue.setAuthority(null);
          metadataValue.setConfidence(confidences == null ? Choices.CF_UNSET : confidences.get(i));
        }
        // authority sanity check: if authority is required, was it supplied?
        // XXX FIXME? can't throw a "real" exception here without changing all the callers to expect
        // it, so use a runtime exception
        if (authorityRequired
            && (metadataValue.getAuthority() == null
                || metadataValue.getAuthority().length() == 0)) {
          throw new IllegalArgumentException(
              "The metadata field \""
                  + metadataField.toString()
                  + "\" requires an authority key but none was provided. Value=\""
                  + values.get(i)
                  + "\"");
        }
      }
      if (values.get(i) != null) {
        // remove control unicode char
        String temp = values.get(i).trim();
        char[] dcvalue = temp.toCharArray();
        for (int charPos = 0; charPos < dcvalue.length; charPos++) {
          if (Character.isISOControl(dcvalue[charPos])
              && !String.valueOf(dcvalue[charPos]).equals("\u0009")
              && !String.valueOf(dcvalue[charPos]).equals("\n")
              && !String.valueOf(dcvalue[charPos]).equals("\r")) {
            dcvalue[charPos] = ' ';
          }
        }
        metadataValue.setValue(String.valueOf(dcvalue));
        ;
      } else {
        metadataValue.setValue(null);
      }
      // An update here isn't needed, this is persited upon the merge of the owning object
      //            metadataValueService.update(context, metadataValue);
      dso.addDetails(metadataField.toString());
    }
  }