[FTRL paper](https://research.google.com/pubs/archive/41159.pdf).
*   `Optimizer.__init__` now accepts a `gradient_aggregator` to allow for
    customization of how gradients are aggregated across devices, as well as
    `gradients_transformers` to allow for custom gradient transformations (such
    as gradient clipping).
*   Improvements to Keras preprocessing layers:

  - [Changelog since v1.19.14](#changelog-since-v11914)
  - [Important Security Information](#important-security-information)
    - [CVE-2021-25741: Symlink Exchange Can Allow Host Filesystem Access](#cve-2021-25741-symlink-exchange-can-allow-host-filesystem-access)
  - [Changes by Kind](#changes-by-kind-1)
    - [Bug or Regression](#bug-or-regression-1)
    - [Other (Cleanup or Flake)](#other-cleanup-or-flake)

$font-family-monospace;\n  @include font-size(1em); // Correct the odd `em` font sizing in all browsers.\n}\n\npre {\n  // Remove browser default top margin\n  margin-top: 0;\n  // Reset browser default of `1em` to use `rem`s\n  margin-bottom: 1rem;\n  // Don't allow content to break outside\n  overflow: auto;\n  // Disable auto-hiding scrollbar in IE & legacy Edge to avoid overlap,\n  // making it impossible to interact with the content\n  -ms-overflow-style: scrollbar;\n}\n\n\n//\n// Figures\n//\n\nfigure {\n...

$font-family-monospace;\n  @include font-size(1em); // Correct the odd `em` font sizing in all browsers.\n}\n\npre {\n  // Remove browser default top margin\n  margin-top: 0;\n  // Reset browser default of `1em` to use `rem`s\n  margin-bottom: 1rem;\n  // Don't allow content to break outside\n  overflow: auto;\n}\n\n\n//\n// Figures\n//\n\nfigure {\n  // Apply a consistent margin strategy (matches our type styles).\n  margin: 0 0 1rem;\n}\n\n\n//\n// Images and content\n//\n\nimg {\n  vertical-align: middle;\n...

              - provider
            properties:
              action:
                description: |-
                  Optional.

                  Valid Options: ALLOW, DENY, AUDIT, CUSTOM
                enum:
                - ALLOW
                - DENY
                - AUDIT
                - CUSTOM
                type: string
              provider: