code: private void insertPending() {
          for (Pair<Integer, T> pi : mPendingItemsToInsert) {
              for (AtomicInteger existing : mActiveIndexes) {
                  if (existing.intValue() >= pi.first) {
                      existing.incrementAndGet();
                  }
              }
              mActiveIndexes.add(new AtomicInteger(pi.first));
              mInsertable.add(pi.first, pi.second);
          }
          mPendingItemsToInsert.clear();
      }
docs: Inserts pending items into the Insertable, and adds them to the active positions (correctly managing position shifting). Clears the pending items.