message: Adding deprecation warning for `lr` argument in optimizers.
diff: @@ -22,6 +22,7 @@ from __future__ import print_function
  import abc
  import contextlib
  import functools
  +import warnings
  import six
  @@ -376,6 +377,9 @@ class OptimizerV2(trackable.Trackable):
  # checks that all keyword arguments are non-negative.
  if kwargs[k] is not None and kwargs[k] < 0:
  raise ValueError("Expected {} >= 0, received: {}".format(k, kwargs[k]))
  + if k == "lr":
  + warnings.warn(
  + "The `lr` argument is deprecated, use `learning_rate` instead.")
  self._use_locking = True
  self._init_set_name(name)
  