OESFeedQueue

    /**
     * sortedScoreTreeSet  : Keep all score entries into sorted order.
     * trackScoreShuffler : Provide the Map of uniqueue Id and their timestamp based on score, it
     * provides the uniqueue Id for the oldest entry for given score. As there can be multiple item of same score, 
     * that's why used linkedHashMap
     * trackScoreMap : Used to check if a item entry is present into the queue and return the item 
     */
    private var sortedScoreTreeSet //<score>
            : TreeSet<Float>
    private var trackScoreShuffler // <score, LinkedHashMap<uniqueId, timestamp>
            : ConcurrentHashMap<Float, LinkedHashMap<String, Long>>
    private var trackScoreMap //<uniqueId, OESFeedItem>
            : ConcurrentHashMap<String, T>