public class TimedCache<K>
The key is any object/hash-code
The value is time-stamp in milliseconds
The time interval denotes the interval for which the entry should remain in the hashmap.
If an entry is present in the Linkedhashmap, it does not mean that it's valid (recently seen)
Always try to update the cache and set the last-seen value for this key.
Return true, if a valid existing field was updated, else return false.
(note: if multiple threads update simultaneously, one of them will succeed,
other wills return false)