Cache OnChanged callback

CacheObserverOnChanged.kt

override fun onChanged() {
            Timber.d("items added or moved")
            if (cachedItems.isEmpty())
                return

            val iterator: MutableIterator<String> = cachedItems.keys.iterator()

            val newItemsIds = mutableSetOf<String>()

            for (newIndex in 0 until itemCount) {
                val itemId = getItemId(newIndex)
                newItemsIds.add(itemId)
            }

            //Remove cached items which are not in new set
            while (iterator.hasNext()) {
                val cachedItemId = iterator.next()
                val holder = cachedItems[cachedItemId]
                if (holder?.bindingAdapterPosition == -1 || !newItemsIds.contains(cachedItemId)) {
                    holder?.itemView?.let { view ->
                        if (view.isAttachedToWindow || view.parent != null) {
                            recyclerView?.removeView(view)
                            view.visibility = View.GONE
                        }
                    }
                    iterator.remove()
                }
            }
        }