code: public static KeyValue getReferenceKeyValue(byte[] rowkey, String propertyName,
              String schemaName, List<BeanId> refs, UniqueIds uids) {
          final byte[] pid = uids.getUsid().getId(propertyName);
          final byte[] sid = uids.getUsid().getId(schemaName);
          final byte[] qual = new byte[] { sid[0], sid[1], pid[0], pid[1] };
          final byte[] iids = getIids2(refs, uids);
          return new KeyValue(rowkey, REF_COLUMN_FAMILY, qual, iids);
      }
docs: Get a particular type of references identified by propertyName into key value
  form.
  @param schemaName