`tf.distribute.experimental.ParameterServerStrategy`:
    *   Replaces the existing
        `tf.distribute.experimental.ParameterServerStrategy` symbol with a new
        class that is for parameter server training in TF2. Usage of the old
        symbol, usually with Estimator API, should be **replaced** with
        [`tf.compat.v1.distribute.experimental.ParameterServerStrategy`].

# errors.
# There is ongoing work on Bazel team's side to provide support for transitive
# shared libraries. As part of migrating to transitive shared libraries, we
# hope to provide a better mechanism for control over symbol exporting, and
# then tackle this issue again.
#
# TODO: Remove the following two lines once TF doesn't depend on Bazel wrapping
# all library archives in -whole_archive -no_whole_archive.