code: public Collection<?> persist(Collection<?> objColl, Mutator<byte[]> m) {
      if (null == objColl) {
        throw new IllegalArgumentException("object to save cannot be null");
      }
  
      objMapper.saveObjCollection(keyspace, objColl, m);
      return objColl;
    }
docs: Save the list of entity intances.
  
  @param objColl
  @return