I tried this, and it works for me (buildToolsVersion: 24.0.1):
<ImageView
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_margin="8dp"
android:scaleType="centerInside"
app:imageResource="@{item.avatarResId}"/>
just use app:imageResource to replace android:src, android:src="@{item.avatarResId}" doesn't works else define a custom @BindAdapter("android:src") for it.
but use app:imageResource doesn't need define a @BindAdapter additionally, because the ImageView has a method called setImageResource(), when you use app:imageResource, it will call setImageResource() automatically.