* string literal is of the form {@code "http://[2001:db8::1]:8888/index.html"}.
   *
   * <p>Use of either {@link InetAddresses#toAddrString}, {@link InetAddress#getHostAddress()}, or
   * this method is recommended over {@link InetAddress#toString()} when an IP address string
   * literal is desired. This is because {@link InetAddress#toString()} prints the hostname and the
   * IP address string joined by a "/".
   *

 *       {@link #threadAssertTrue}, {@link #threadAssertEquals}, or {@link #threadAssertNull}, (not
 *       {@code fail}, {@code assertTrue}, etc.) It is OK (but not particularly recommended) for
 *       other code to use these forms too. Only the most typically used JUnit assertion methods are
 *       defined this way, but enough to live with.

 * number.
 *
 * <p>Users of these utilities must be <i>extremely careful</i> not to mix up signed and unsigned
 * {@code long} values. When possible, it is recommended that the {@link UnsignedLong} wrapper class
 * be used, at a small efficiency penalty, to enforce the distinction in the type system.
 *
 * <p>See the Guava User Guide article on <a

 * {@linkplain #servicesByState inspecting} a collection of {@linkplain Service services}.
 * Additionally, users can monitor state transitions with the {@linkplain Listener listener}
 * mechanism.
 *
 * <p>While it is recommended that service lifecycles be managed via this class, state transitions
 * initiated via other mechanisms do not impact the correctness of its methods. For example, if the

 *       {@link #threadAssertTrue}, {@link #threadAssertEquals}, or {@link #threadAssertNull}, (not
 *       {@code fail}, {@code assertTrue}, etc.) It is OK (but not particularly recommended) for
 *       other code to use these forms too. Only the most typically used JUnit assertion methods are
 *       defined this way, but enough to live with.

   * The {@link Iterators} analog to this method is {@link Iterators#getNext}.
   *
   * <p>If no default value is desired (and the caller instead wants a {@link
   * NoSuchElementException} to be thrown), it is recommended that {@code
   * iterable.iterator().next()} is used instead.
   *
   * <p>To get the only element in a single-element {@code Iterable}, consider using {@link

 *
 * <h3>Non-preconditions</h3>
 *
 * <p>It is of course possible to use the methods of this class to check for invalid conditions
 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
 * misleading to future readers of the code and of stack traces. See <a
 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures

   * CacheLoader#reload}.
   *
   * <p>As the default implementation of {@link CacheLoader#reload} is synchronous, it is
   * recommended that users of this method override {@link CacheLoader#reload} with an asynchronous
   * implementation; otherwise refreshes will be performed during unrelated cache read and write
   * operations.
   *

   * its contents, and {@code function} -- <i>not</i> by serializing the transformed values. This
   * can lead to surprising behavior, so serializing the returned list is <b>not recommended</b>.
   * Instead, copy the list using {@link ImmutableList#copyOf(Collection)} (for example), then
   * serialize the copy. Other methods similar to this do not implement serialization at all for
   * this reason.
   *

 *       noted in the method descriptions below.
 *   <li>Streams include primitive-specialized variants such as {@code IntStream}, the use of which
 *       is strongly recommended.
 *   <li>Streams are standard Java, not requiring a third-party dependency.
 * </ul>
 *
 * <h3>Example</h3>
 *
 * <p>Here is an example that accepts a list from a database call, filters it based on a predicate,