- The alpha feature `AnyVolumeDataSource` enables PersistentVolumeClaim objects to use the spec.dataSource field to reference a custom type as a data source ([#88636](https://github.com/kubernetes/kubernetes/pull/88636), [@bswartz](https://github.com/bswartz)) [SIG Apps and Storage]

  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))

## Changelog since v1.17.3

## Changes by Kind

### API Change

- Fixes a regression with clients prior to 1.15 not being able to update podIP in pod status, or podCIDR in node spec, against >= 1.16 API servers ([#88505](https://github.com/kubernetes/kubernetes/pull/88505), [@liggitt](https://github.com/liggitt)) [SIG Apps and Network]

### Other (Bug, Cleanup or Flake)

    Kubernetes-managed containers on the node.
  * It is not compatible with CNI plugins that do not conform to the
    [error handling behavior in the spec](https://github.com/containernetworking/cni/blob/master/SPEC.md#network-configuration-list-error-handling).
    The plugins are being updated to resolve this issue ([#43488](https://github.com/kubernetes/kubernetes/issues/43488)).

- github.com/moby/term: [9d4ed18 → 3f7ff69](https://github.com/moby/term/compare/9d4ed18...3f7ff69)
- github.com/opencontainers/image-spec: [v1.0.1 → v1.0.2](https://github.com/opencontainers/image-spec/compare/v1.0.1...v1.0.2)
- github.com/opencontainers/runc: [v1.0.2 → v1.1.1](https://github.com/opencontainers/runc/compare/v1.0.2...v1.1.1)

- CustomResourceDefinitions added support for marking versions as deprecated by setting `spec.versions[*].deprecated` to `true`, and for optionally overriding the default deprecation warning with a `spec.versions[*].deprecationWarning` field. ([#92329](https://github.com/kubernetes/kubernetes/pull/92329), [@liggitt](https://github.com/liggitt)) [SIG API Machinery]

- When using `kubectl replace` (or the equivalent API call) on a Service, the caller no longer needs to do a read-modify-write cycle to fetch the allocated values for `.spec.clusterIP` and `.spec.ports[].nodePort`.  Instead the API server will automatically carry these forward from the original object when the new object does not specify them. ([#104674](https://github.com/kubernetes/kubernetes/pull/104674), [@thockin](https://github.com/thockin))...

    assertThat(Booleans.falseFirst().compare(true, false)).isGreaterThan(0);
  }

  public void testCompare() {
    for (boolean x : VALUES) {
      for (boolean y : VALUES) {
        // note: spec requires only that the sign is the same
        assertWithMessage(x + ", " + y)
            .that(Booleans.compare(x, y))
            .isEqualTo(Boolean.valueOf(x).compareTo(y));
      }
    }
  }

        .build()
  }

  @AfterEach
  fun tearDown() {
    ResponseCache.setDefault(null)
    cache.delete()
  }

  /**
   * Test that response caching is consistent with the RI and the spec.
   * http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.4
   */
  @Test
  fun responseCachingByResponseCode() {
    // Test each documented HTTP/1.1 code, plus the first unused value in each range.

## Changelog since v1.15.3

### Other notable changes

* Restores compatibility with kubectl client-side validation when structural schemas are present in a CRD which sets spec.preserveUnknownFields=true ([#82666](https://github.com/kubernetes/kubernetes/pull/82666), [@liggitt](https://github.com/liggitt))