public void notifySectionDataSetChanged(int sectionIndex) {
        if (sections == null) {
            buildSectionIndex();
            notifyAllSectionsDataSetChanged();
        } else {
            buildSectionIndex();
            Section section = this.sections.get(sectionIndex);
            notifyItemRangeChanged(section.adapterPosition, section.length);
        }

        // clear item selection state
        getSectionSelectionState(sectionIndex).items.clear();
    }
Notify that all the items in a particular section are invalid and that section should be reloaded
Never directly call notifyDataSetChanged.
This will clear item selection state for the affected section.

@param sectionIndex index of the section to reload.
android/modules/module_common/src/main/java/github/tornaco/android/thanos/widget/section/SectioningAdapter.java