code: public int getPosition(long identifier) {
          int position = 0;
          for (IAdapter<Item> adapter : mAdapters) {
              if (adapter.getOrder() < 0) {
                  continue;
              }
  
              int relativePosition = adapter.getAdapterPosition(identifier);
              if (relativePosition != -1) {
                  return position + relativePosition;
              }
              position = adapter.getAdapterItemCount();
          }
  
          return -1;
      }
docs: Searches for the given item and calculates its global position
  
  @param identifier the identifier of an item which is searched for
  @return the global position, or -1 if not found