* href="https://docs.oracle.com/javase/tutorial/java/generics/genTypeInference.html#type-inference-instantiation">"diamond"
   * syntax</a>.
   *
   * <p>Overall, this method is not very useful and will likely be deprecated in the future.
   */
  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call

abstract class AbstractMapBasedMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimap<K, V> implements Serializable {
  /*
   * Here's an outline of the overall design.
   *
   * The map variable contains the collection of values associated with each
   * key. When a key-value pair is added to a multimap that didn't previously

   *
   * <p>This method refines {@link Collection#add}, which only <i>ensures</i> the presence of the
   * element, to further specify that a successful call must always increment the count of the
   * element, and the overall size of the collection, by one.
   *
   * <p>To both add the element and obtain the previous count of that element, use {@link
   * #add(Object, int) add}{@code (element, 1)} instead.
   *

   *
   * <p>This method refines {@link Collection#add}, which only <i>ensures</i> the presence of the
   * element, to further specify that a successful call must always increment the count of the
   * element, and the overall size of the collection, by one.
   *
   * <p>To both add the element and obtain the previous count of that element, use {@link
   * #add(Object, int) add}{@code (element, 1)} instead.
   *

   * the problem impacts just one stream or the entire connection.
   *
   * To differentiate the two cases we ping the server when a stream times out. If the overall
   * connection is fine the ping will receive a pong; otherwise it won't.
   *
   * The deadline to respond to this ping attempts to limit the cost of being wrong. If it is too

     * this client silently recovers from the following problems:
     *
     * * **Unreachable IP addresses.** If the URL's host has multiple IP addresses,
     *   failure to reach any individual IP address doesn't fail the overall request. This can
     *   increase availability of multi-homed services.
     *
     * * **Stale pooled connections.** The [ConnectionPool] reuses sockets

- Overall, enable the feature of `PreferNominatedNode` will  improve the performance of scheduling where preemption might frequently happen, but in theory, enable the feature of `PreferNominatedNode`, the pod might not be scheduled to the best candidate node...

- The new `dra_resource_claims_in_use` kubelet metrics reported active `ResourceClaims`, overall and by driver. ([#131641](https://github.com/kubernetes/kubernetes/pull/131641), [@pohly](https://github.com/pohly)) [SIG Architecture, Instrumentation, Node and Testing]

   ([#123271](https://github.com/kubernetes/kubernetes/pull/123271), [@neolit123](https://github.com/neolit123))
- kubeadm: improved the overall logic, error handling, and output messages when waiting for the kubelet and API server `/healthz` endpoints to return `OK`. The kubelet and API server checks no longer ran in parallel, but one after another (in serial).

  - If all QueueingHintFn return QueueSkip, it puts this pod back to the unschedulable pod pool
  
  Having appropriate QueueingHintFn contributes to reducing useless retries and thus improves the overall scheduler's performance.
  
  **How can I migrate?**
  
  For backward compatibility, nil `QueueingHintFn` is treated as always returning QueueAfterBackoff.