public void setCumulator(Cumulator cumulator) {
        if (cumulator == null) {
            throw new NullPointerException("cumulator");
        }
        this.cumulator = cumulator;
    }
Set the {@link Cumulator} to use for cumulate the received {@link ByteBuf}s.
src/main/java/com/alipay/remoting/codec/AbstractBatchDecoder.java