docs: protected FastAdapter<IDrawerItem> getAdapter() {
          if (mAdapter == null) {
              mAdapter = FastAdapter.with(Arrays.asList(mHeaderAdapter, mItemAdapter, mFooterAdapter), Arrays.<IAdapterExtension<IDrawerItem>>asList(mExpandableExtension));
              mAdapter.withSelectable(true);
              mAdapter.withMultiSelect(false);
              mAdapter.withAllowDeselection(false);
              mAdapter.setHasStableIds(mHasStableIds);
          }
          return mAdapter;
      }