private HeapEvictor getHeapEvictor() {
    return evictor;
  }
Takes delta to be evicted and tries to evict the least no of LRU entry which would make
evictedBytes more than or equal to the delta

@since GemFire 6.0
geode-core/src/main/java/org/apache/geode/internal/cache/eviction/RegionEvictorTask.java