code: public List<ElementSubSet<E>> getPartitions() {
          final List<ElementSubSet<E>> partitions = new ArrayList<>();
          forEachPartition((idx, key, from, to) -> {
              partitions.add(new ElementSubSet<>(SplittableElementSet.this, key, from, to));
              return true;
          });
          return partitions;
      }
docs: Get all the partitions as subsets.
  
  @return a collection of {@link ElementSubSet}.