<layout xmlns:andr...
    <data>
    </data>
       <include layout="@layout/buttons"></include>
....

<layout xmlns:andr...>
    <data>
    </data>
    <Button
        android:id="@+id/button"
        ...." />

... binding = DataBindingUtil.inflate...
binding.button; ->cannot resolve symbol 'button'

<layout xmlns:andr...>
  <data>
    <variable name="foo" type="int"/>
  </data>
  <Button
    android:id="@+id/button"
    ...." />

<layout xmlns:andr...
...
   <include layout="@layout/buttons"
            android:id="@+id/buttons"
            app:foo="@{1}"/>
....

MainBinding binding = MainBinding.inflate(getLayoutInflater());
binding.buttons.button

<layout xmlns:andr...>
  <Button
    android:id="@+id/button"
    ...." />

<layout xmlns:andr...
...
   <include layout="@layout/buttons"
            android:id="@+id/buttons"/>
....