public Item withByteBufferSet(String attrName, Set<ByteBuffer> val) {
        checkInvalidAttribute(attrName, val);
        // convert ByteBuffer to bytes to keep Jackson happy
        Set<byte[]> set = new LinkedHashSet<byte[]>(val.size());
        for (ByteBuffer bb: val)
            set.add(copyBytesFrom(bb));
        attributes.put(attrName, set);
        return this;
    }
Sets the value of the specified attribute in the current item to the
given value.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/Item.java