Check a deep nest object properties in an elegant(Functional Programming) way.

deep_null_check.java

Optional.ofNullable(product).map(
            Product::getLatestVersion
        ).map(
            ProductVersion::getProductData
        ).map(
            ProductData::getTradeItem
        ).map(
            TradeItemType::getInformationProviderOfTradeItem
        ).map(
            PartyInRoleType::getGln
        ).orElse(null);
        
int entryListSize =  io.vavr.control.Option.of(dataResponse)
    .map(Response::data)
    .map(FetchEntriesOfFeedQuery.Data::feed)
    .map(FetchEntriesOfFeedQuery.Feed::entries)
    .map(List::size)
    .getOrElse(0);        

Note: Lambda needs the API of Android >= 24.