message: Remove warnings in tf.losses.softmax_cross_entropy
  This fix tries to address the issue raised in 16534 where
  tf.losses.softmax_cross_entropy causes warnings due
  to the calling of tf.nn.softmax_cross_entropy_with_logits.
  This fix switches to tf.nn.softmax_cross_entropy_with_logits_v2
  to remove the warning.
  This fix fixes 16534.
diff: @@ -726,9 +726,12 @@ def softmax_cross_entropy(
  smooth_negatives = label_smoothing / num_classes
  onehot_labels = onehot_labels * smooth_positives + smooth_negatives
  - losses = nn.softmax_cross_entropy_with_logits(labels=onehot_labels,
  - logits=logits,
  - name="xentropy")
  + onehot_labels = array_ops.stop_gradient(
  + onehot_labels, name="labels_stop_gradient")
  + losses = nn.softmax_cross_entropy_with_logits_v2(
  + labels=onehot_labels, logits=logits, name="xentropy")
  +
  +
  return compute_weighted_loss(
  losses, weights, scope, loss_collection, reduction=reduction)
  