*   Losses are scaled in canned estimator v2 and not in the optimizers
        anymore. If you are using Estimator + distribution strategy + optimikzer
        v1 then the behavior does not change. This implies that if you are using
        custom estimator with optimizer v2, you have to scale losses. We have
        new utilities to help scale losses `tf.nn.compute_average_loss`,
        `tf.nn.scale_regularization_loss`.