Replace your recyclerView with,

<android.support.v4.widget.NestedScrollView
<android.support.v7.widget.RecyclerView
 android:id="@+id/conversation"
 app:layout_behavior="@string/appbar_scrolling_view_behavior"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" />
</android.support.v4.widget.NestedScrollView>

will manage the rest of things.

One more thing, no need to put your recyclerView inside NestedScrollView

http://stackoverflow.com/questions/31000081/how-to-use-recyclerview-inside-nestedscrollview

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