public static ByteBufferSend sizePrefixed(ByteBuffer buffer) {
        ByteBuffer sizeBuffer = ByteBuffer.allocate(4);
        sizeBuffer.putInt(0, buffer.remaining());
        return new ByteBufferSend(sizeBuffer, buffer);
    }
A send backed by an array of byte buffers
clients/src/main/java/org/apache/kafka/common/network/ByteBufferSend.java