docs: @NonNull
      @Override
      @UiThread
      public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
          if (isParentViewType(viewType)) {
              PVH pvh = onCreateParentViewHolder(viewGroup, viewType);
              pvh.setParentViewHolderExpandCollapseListener(mParentViewHolderExpandCollapseListener);
              pvh.mExpandableAdapter = this;
              return pvh;
          } else {
              CVH cvh = onCreateChildViewHolder(viewGroup, viewType);
              cvh.mExpandableAdapter = this;
              return cvh;
          }
      }