### Question:
UpdateRequest { public static Builder builder() { return new Builder(); } private  UpdateRequest(Builder builder); static Builder builder(); @Nullable
    final SelectorFunction<Collection<Flash>, Flash> flashSelector; @Nullable
    final SelectorFunction<Collection<FocusMode>, FocusMode> focusModeSelector; }### Answer:
@Test public void build() throws Exception { UpdateRequest updateRequest = UpdateRequest.builder() .flash(flashSelector) .focusMode(focusModeSelector) .build(); assertSame(flashSelector, updateRequest.flashSelector); assertSame(focusModeSelector, updateRequest.focusModeSelector); }