code: @Nullable
      private String getItemKey(int position) {
          if (mMap != null) {
              return new ArrayList<>(mMap.entrySet()).get(position).getKey();
          } else if (mJsonArray != null) {
              return String.valueOf(position);
          }
          return null;
      }
docs: Provides the item key name. Number for array, property for object.
  
  @param position The position.
  @return The key as string or null.