protected synchronized EvictionNode unlinkTailEntry() {
    EvictionNode evictionNode = tail.previous();
    if (evictionNode == head) {
      return null; // end of eviction list
    }

    unlinkEntry(evictionNode);
    return evictionNode;
  }
Adds an lru node to the tail of the list.
geode-core/src/main/java/org/apache/geode/internal/cache/eviction/AbstractEvictionList.java