A potential NPE bug

Hi all, our bug scanner has reported a NPE bug.

A possible call chain may be getNode() => LRUMap.java#L65 => LRUMap.java#L68. Since the method getNode() may return null at LRUMap.java#L118, a NPE bug may take place at LRUMap.java#L76 when the variable node is null.

Thanks.