* }</pre>
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the discussion in the {@link #addListener} documentation. All its warnings about heavyweight
   * listeners are also applicable to heavyweight functions passed to this method.
   *
   * <p>This method is similar to {@link java.util.concurrent.CompletableFuture#exceptionally}. It

   * we wanted to support legacy classes that implement the raw type {@code Comparable} (instead of
   * implementing {@code Comparable<Foo>}) without producing warnings. If so, we would prefer today
   * to produce warnings in that case, and we may change this method to do so in the future. Support
   * for raw {@code Comparable} types in Guava in general is tracked as <a

   * "plain {@code T}." This API provides that.
   */
  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
  // The warnings are legitimate. Each time we use this method, we document why.
  @ParametricNullness
  static <T extends @Nullable Object> T uncheckedNull() {
    return null;
  }

  private NullnessCasts() {}

   * we wanted to support legacy classes that implement the raw type {@code Comparable} (instead of
   * implementing {@code Comparable<Foo>}) without producing warnings. If so, we would prefer today
   * to produce warnings in that case, and we may change this method to do so in the future. Support
   * for raw {@code Comparable} types in Guava in general is tracked as <a

    return t;
  }

  /** Returns {@code null} as any type, even one that does not include {@code null}. */
  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
  // The warnings are legitimate. Each time we use this method, we document why.
  @ParametricNullness
  static <T extends @Nullable Object> T unsafeNull() {
    return null;
  }

  private NullnessCasts() {}

-   [guava-discuss: For open-ended questions and discussion](https://groups.google.com/group/guava-discuss)

## IMPORTANT WARNINGS

1. APIs marked with the `@Beta` annotation at the class or method level
are subject to change. They can be modified in any way, or even
removed, at any time. If your code is a library itself (i.e. it is

 * way to check an object at runtime to be an instance of a {@link TypeToken}. Instead, caller
 * should use the type safe {@link #putInstance}.
 *
 * <p>Also, if caller suppresses unchecked warnings and passes in an {@code Iterable<String>} for
 * type {@code Iterable<Integer>}, the map won't be able to detect and throw type error.
 *

-   [guava-discuss: For open-ended questions and discussion](https://groups.google.com/group/guava-discuss)

## IMPORTANT WARNINGS

1.  APIs marked with the `@Beta` annotation at the class or method level are
    subject to change. They can be modified in any way, or even removed, at any

   * more futures or adding more {@code directExecutor()} listeners inline -- consider {@link
   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using

              restoreInterruptIfIsInterruptedException(e);
              logger.get().log(WARNING, "thrown by close()", e);
            }
          });
    } catch (RejectedExecutionException e) {
      if (logger.get().isLoggable(WARNING)) {
        logger
            .get()
            .log(
                WARNING,
                String.format("while submitting close to %s; will close inline", executor),