docs: private Pair<Integer, Integer> getItemPosition(final int packedPosition) {
          int currentPosition = packedPosition;
          int groupIndex = -1;
          int childIndex = -1;
          int numColumns = getNumColumnsCompatible();
  
          for (int i = 0; i < getExpandableListAdapter().getGroupCount(); i++) {
              if (currentPosition == 0) {
                  groupIndex = i;
                  break;
              } else if (currentPosition < numColumns) {
                  break;
              } else {
                  currentPosition -= numColumns;
  
                  if (isGroupExpanded(i)) {
                      int childCount = getExpandableListAdapter().getChildrenCount(i);
  
                      if (currentPosition < childCount) {
                          groupIndex = i;
                          childIndex = currentPosition;
                          break;
                      } else {
                          int lastLineCount = childCount % numColumns;
                          currentPosition -=
                                  childCount + (lastLineCount > 0 ? numColumns - lastLineCount : 0);
                      }
                  }
              }
          }
  
          return new Pair<>(groupIndex, childIndex);
      }