@Nullable
  private synchronized Bucket<V> getBucketIfPresent(int bucketedSize) {
    return mBuckets.get(bucketedSize);
  }
Gets the freelist for the specified bucket if it exists.

@param bucketedSize the bucket size
@return the freelist for the bucket
imagepipeline/src/main/java/com/facebook/imagepipeline/memory/BasePool.java