code: public void insert(@NonNull T object, int index) {
          synchronized (mLock) {
              mObjects.add(index, object);
              notifyItemInserted(index);
          }
      }
docs: Inserts the specified object at the specified index in the array.
  
  @param object The object to insert into the array.
  @param index  The index at which the object must be inserted.