boolean evictBucketEntryIfNoRpcReferenced(BlockCacheKey blockCacheKey, BucketEntry bucketEntry) {
    if (!bucketEntry.isRpcRef()) {
      return doEvictBlock(blockCacheKey, bucketEntry, true);
    }
    return false;
  }
Evict {@link BlockCacheKey} and its corresponding {@link BucketEntry} only if
{@link BucketEntry#isRpcRef} is false. <br/>
NOTE:When evict from {@link BucketCache#backingMap},only the matched {@link BlockCacheKey} and
{@link BucketEntry} could be removed.
@param blockCacheKey {@link BlockCacheKey} to evict.
@param bucketEntry   {@link BucketEntry} matched {@link BlockCacheKey} to evict.
@return true to indicate whether we've evicted successfully or not.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java