Should we first call MobileAds.setRequestConfiguration or MobileAds.initialize?

According to Google Developer support, the following is the right way to do

https://groups.google.com/forum/#!category-topic/google-admob-ads-sdk/android/17oVu0sABjs

RequestConfiguration conf= new RequestConfiguration.Builder()
        .setMaxAdContentRating(
                MAX_AD_CONTENT_RATING_T)
        .build();

MobileAds.setRequestConfiguration(conf);
MobileAds.initialize(context, APP_ID);