can"t benefit from incremental build acceleration, because on every
       execution it sees that the classpath has changed, and so to be
       safe, it needs to re-run.

       - This is unfortunate, because actually it would be safe to declare
       the task as up-to-date, because these two files, which are based on
       the generated index.xml, are outputs, not inputs. We can be sure of

    // - even for the JVM in our open-source release (https://github.com/google/guava/issues/3147)
    // If anyone in our monorepo uses the Android copy of Guava on a JVM, that would be unfortunate.
    // But that is only likely to happen in Robolectric tests, where the risks of JDK regex are low.
    return new JdkPatternCompiler();
  }

   * trouble than just using Object.class.)
   *
   * Then we declare the getters for these fields as @GwtIncompatible so that no one can try to use
   * them under J2CL—or, as an unfortunate side effect, under GWT. We do still give the fields
   * themselves their proper values under GWT, since GWT's EnumMap does need the Class instance.
   *

   * trouble than just using Object.class.)
   *
   * Then we declare the getters for these fields as @GwtIncompatible so that no one can try to use
   * them under J2CL—or, as an unfortunate side effect, under GWT. We do still give the fields
   * themselves their proper values under GWT, since GWT's EnumMap does need the Class instance.
   *

#### Rationale

- SSE-C requires application to remember the keys for all GET/PUT operations, any unfortunate loss of keys would automatically mean the objects cannot be accessed anymore.
- SSE-C is hardly adopted by most widely used applications, applications prefer server to manage the keys via SSE-KMS or SSE-S3.

	for len(features) > 0 || len(required) > 0 {
		switch {
		case len(features) == 0 || (len(required) > 0 && required[0] < features[0]):
			feature := take(&required)
			if exceptionSet[feature] {
				// An "unfortunate" case: the feature was once
				// included in the API (e.g. go1.txt), but was
				// subsequently removed. These are already
				// acknowledged by being in the file
				// "api/except.txt". No need to print them out

     * the parameter and return type both to be platform types. As a result, Kotlin permits calls
     * that can lead to NullPointerException. That's unfortunate. But hopefully most Kotlin callers
     * use `get(key) ?: defaultValue` instead of this method, anyway.
     */
    V result = get(key);

     * the parameter and return type both to be platform types. As a result, Kotlin permits calls
     * that can lead to NullPointerException. That's unfortunate. But hopefully most Kotlin callers
     * use `get(key) ?: defaultValue` instead of this method, anyway.
     */
    V result = get(key);

  `I see!' said the Queen, who had meanwhile been examining the
roses.  `Off with their heads!' and the procession moved on,
three of the soldiers remaining behind to execute the unfortunate
gardeners, who ran to Alice for protection.

  `You shan't be beheaded!' said Alice, and she put them into a
large flower-pot that stood near.  The three soldiers wandered

   * // impossible for a non-String to be in the intersection
   * SuppressWarnings("unchecked")
   * Set<String> badStrings = (Set) Sets.intersection(aFewBadObjects, manyBadStrings);
   * }
   *
   * <p>This is unfortunate, but should come up only very rarely.
   */
  public static <E extends @Nullable Object> SetView<E> intersection(Set<E> set1, Set<?> set2) {
    checkNotNull(set1, "set1");
    checkNotNull(set2, "set2");