docs: private synchronized void initBuckets() {
      final SparseIntArray bucketSizes = mPoolParams.bucketSizes;
  
      // create the buckets
      if (bucketSizes != null) {
        fillBuckets(bucketSizes);
        mAllowNewBuckets = false;
      } else {
        mAllowNewBuckets = true;
      }
    }