/**
     * Returns immutable system properties to use for interpolation. The system properties are collected from the
     * runtime environment such as {@link System#getProperties()} and environment variables
     * (prefixed with {@code env.}).
     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

    /**

import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/storage/v1";

// CSIDriver captures information about a Container Storage Interface (CSI)
// volume driver deployed on the cluster.

     * reflection implementation.
     */
    try {
      new TypeToken<T>() {};
      fail();
    } catch (IllegalStateException expected) {
      // Type variables aren't allowed.
    }
  }

  public void testRawTypeIsCorrect() {
    TypeToken<List<String>> token = new TypeToken<List<String>>() {};
    assertEquals(List.class, token.getRawType());
  }

- Added options for configuring `nf_conntrack_udp_timeout`, and `nf_conntrack_udp_timeout_stream` variables of netfilter conntrack subsystem. ([#120808](https://github.com/kubernetes/kubernetes/pull/120808), [@aroradaman](https://github.com/aroradaman))

- Kubeadm: fix an issue with the kube-proxy container env. variables ([#84888](https://github.com/kubernetes/kubernetes/pull/84888), [@neolit123](https://github.com/neolit123))

### ConfigMap
* Volumes and environment variables populated from ConfigMap and Secret objects can now tolerate the named source object or specific keys being missing, by adding `optional: true` to the volume or environment variable source specifications. ([#39981](https://github.com/kubernetes/kubernetes/pull/39981), [@fraenkel](https://github.com/fraenkel))

import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";
import "k8s.io/apimachinery/pkg/util/intstr/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/apps/v1beta2";

// DEPRECATED - This group version of ControllerRevision is deprecated by apps/v1/ControllerRevision. See the
// release notes for more information.

* Remove environment variables and internal Kubernetes Docker labels from cAdvisor Prometheus metric labels. ([#31064](https://github.com/kubernetes/kubernetes/pull/31064), [@grobie](https://github.com/grobie))
    * Old behavior:

- Added a alpha feature, behind the `RelaxedEnvironmentVariableValidation` feature gate.
  When that gate is enabled, Kubernetes allows almost all printable ASCII characters to be used in the names
  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))

      }
    }

    // Serialization invokes writeObject only when it's private.
    // The SynchronizedObject subclasses don't need a writeObject method since
    // they don't contain any non-transient member variables, while the
    // following writeObject() handles the SynchronizedObject members.

    @GwtIncompatible // java.io.ObjectOutputStream
    @J2ktIncompatible