* This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is
   * a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
   *
   * The coding pattern above is heavily used in java.util, e.g. in ArrayList. There is a
   * RangeCheckMicroBenchmark in the JDK that was used to test this.
   *

 *       com.google.common.primitives.Ints#stringConverter Ints.stringConverter} or the {@linkplain
 *       #reverse reverse} views of these.
 *   <li>Convert between specific preset values using {@link
 *       com.google.common.collect.Maps#asConverter Maps.asConverter}. For example, use this to
 *       create a "fake" converter for a unit test. It is unnecessary (and confusing) to <i>mock</i>

 * href="https://github.com/ReactiveX/RxJava/wiki">RxJava</a> (supplemented with its <a
 * href="https://github.com/ReactiveX/RxAndroid">RxAndroid</a> extension if you are building for
 * Android) or <a href="https://projectreactor.io/">Project Reactor</a>. (For the basics of
 * translating code from using an event bus to using a reactive-streams framework, see these two
 * guides: <a href="https://blog.jkl.gg/implementing-an-event-bus-with-rxjava-rxbus/">1</a>, <a

 *       com.google.common.primitives.Ints#stringConverter Ints.stringConverter} or the {@linkplain
 *       #reverse reverse} views of these.
 *   <li>Convert between specific preset values using {@link
 *       com.google.common.collect.Maps#asConverter Maps.asConverter}. For example, use this to
 *       create a "fake" converter for a unit test. It is unnecessary (and confusing) to <i>mock</i>

 * @since 1.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class Callables {
  private Callables() {}

  /** Creates a {@code Callable} which immediately returns a preset value each time it is called. */
  public static <T extends @Nullable Object> Callable<T> returning(@ParametricNullness T value) {
    return () -> value;
  }

  /**

   * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is
   * a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
   *
   * The coding pattern above is heavily used in java.util, e.g. in ArrayList. There is a
   * RangeCheckMicroBenchmark in the JDK that was used to test this.
   *

   * found in {@code /etc/mime.types}, e.g. <a
   * href="http://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x/conf/mime.types"></a> of the
   * Apache <a href="http://httpd.apache.org/">HTTPD project</a>; for the specification, see <a
   * href="http://www.adobe.com/devnet-apps/photoshop/fileformatashtml/PhotoshopFileFormats.htm">
   * Adobe Photoshop Document Format</a> and <a