Fix: horizontal sessions scroll to wrong position on favorited

[kubode]

Issue

• No issue

Overview (Required)

• Fix HorizontalSessionsItem's scroll position is not saved on favorited
• Make RecyclerView.addOnScrollListener to inline function

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個人的なメモ

• [DiffUtil.Callback#getChangePayload](https://developer.android.com/reference/android/support/v7/util/DiffUtil.Callback.html#getChangePayload(int, int))がnullならViewHolderの再生成される。
• その際、同じpositionのViewHolderがもう一つ生成され、newViewHolder.bind -> oldViewHolder.unbindの順で呼ばれる。
• 故に、お気に入りされてnotifyChangeされるとスクロール位置が狂っていた。
• groupieにはpayloadのサポートがない。

[takahirom]

🆒

[takahirom]

This code is one of the places where I took the longest time to implement DroidKaigi 😓

[takahirom]

I don't know about payload

[takahirom]

Does current release have that support? 🤔 https://github.com/lisawray/groupie/blob/master/library/src/main/java/com/xwray/groupie/Section.java#L163

[takahirom]

It probably 2.1.0-alpha1 😓

[takahirom]

Please fix lint warnings 🙇

[kubode]

Fixed 😄

[takahirom]

Probably you can use this format 👍 https://kotlinlang.org/docs/reference/coding-conventions.html#function-formatting

[takahirom]

Can you fix to use normal expression 🙇 Expression functions should not wrap to two lines. If an expression function grows to require wrapping, use a normal function body, a return declaration, and normal expression wrapping rules instead. https://android.github.io/kotlin-guides/style.html#expression-functions

[kubode]

In this case, lambda expression is declaring as default argument. So, I think it can't use normal expression.

[takahirom]

Sorry I made mistake

[takahirom]

I understood. Thanks you! I learned a lot by this pr!👍