code: public <K> void insertMulti(Map<K, String> keyValues, Serializer<K> keySerializer) {
      Mutator<K> m = createMutator(keyspace, keySerializer);
      for (Map.Entry<K, String> keyValue: keyValues.entrySet()) {
        m.addInsertion(keyValue.getKey(), CF_NAME,
            createColumn(COLUMN_NAME, keyValue.getValue(), keyspace.createClock(), serializer, serializer));
      }
      m.execute();
    }
docs: Insert multiple values