*   <li>It is easy for the user to ensure that listeners are never invoked while holding locks.
 * </ul>
 *
 * The last point is subtle. Often the observable object will be managing its own internal state
 * using a lock, however it is dangerous to dispatch listeners while holding a lock because they
 * might run on the {@code directExecutor()} or be otherwise re-entrant (call back into your

   * Parses the specified string as a single-precision floating point value. The ASCII character
   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Float#parseFloat(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Float#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

* Fix garbage collection and resource quota when the controller-manager uses --leader-elect=false ([#57340](https://github.com/kubernetes/kubernetes/pull/57340), [@jmcmeek](https://github.com/jmcmeek))
* kube-apiserver: fixes loading of `--admission-control-config-file` containing AdmissionConfiguration apiserver.k8s.io/v1alpha1 config object ([#58441](https://github.com/kubernetes/kubernetes/pull/58441), [@liggitt](https://github.com/liggitt))

    "input": "aa--",
    "output": "aa--"
  },
  {
    "input": "a†--",
    "output": "xn--a---kp0a"
  },
  {
    "input": "ab--c",
    "output": "ab--c"
  },
  {
    "comment": "Label with leading hyphen",
    "input": "-x",
    "output": "-x"
  },
  {
    "input": "-†",
    "output": "xn----xhn"
  },
  {
    "input": "-x.xn--zca",
    "output": "-x.xn--zca"
  },
  {
    "input": "-x.ß",

* Upgrade Stackdriver Logging Agent addon image to 0.6-1.6.0-1 to use Fluentd v1.2. This provides nanoseconds timestamp granularity for logs. ([#70954](https://github.com/kubernetes/kubernetes/pull/70954), [@qingling128](https://github.com/qingling128))

     * seenExceptionsField to its exception
     *
     * Thread2: calls setException(), which returns false, CASes seenExceptionsField to its
     * exception, and wrongly believes that its exception is new (leading it to logging it when it
     * shouldn't)
     *
     * Our solution is for threads to CAS seenExceptionsField from null to a Set populated with _the
     * initial exception_, no matter which thread does the work. This ensures that

    return asCharSource(url, charset).readLines(callback);
  }

  /**
   * Reads all of the lines from a URL. The lines do not include line-termination characters, but do
   * include other leading and trailing whitespace.
   *
   * <p>This method returns a mutable {@code List}. For an {@code ImmutableList}, use {@code
   * Resources.asCharSource(url, charset).readLines()}.
   *
   * @param url the URL to read from

   * Parses the specified string as a double-precision floating point value. The ASCII character
   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

    assertThat("Thu, 01 Jan 1970 00:00 GMT".toHttpDateOrNull()).isNull()
    // Extra spaces treated as bad.
    assertThat("Thu,  01 Jan 1970 00:00 GMT".toHttpDateOrNull()).isNull()
    // Missing leading zero treated as bad.
    assertThat("Thu, 1 Jan 1970 00:00 GMT".toHttpDateOrNull()).isNull()

    // RFC 850, obsoleted by RFC 1036 with any TZ.
    assertThat("Thursday, 01-Jan-1970 00:00:00 GMT-01:00".toHttpDateOrNull()!!.time)

    return new CompactHashMap<>(expectedSize);
  }

  private static final Object NOT_FOUND = new Object();

  /**
   * Maximum allowed false positive probability of detecting a hash flooding attack given random
   * input.
   */
  @VisibleForTesting(
      )
  static final double HASH_FLOODING_FPP = 0.001;

  /**