@Override
    protected void encodeThis(ByteBuffer buffer) {
        super.encodeThis(buffer); // takes care of index bytes
    }
Returns a subitem as a block item,

@param index
           the (0-base) index of the item to return
@throws IndexOutOfBoundsException
            if there is no subitem at index
container-search/src/main/java/com/yahoo/prelude/query/PhraseItem.java