* there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its

 * guaranteed to be supported by all Java platform implementations.
 *
 * <p>Assuming you're free to choose, note that <b>{@link #UTF_8} is widely preferred</b>.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/StringsExplained#charsets">{@code Charsets}</a>.
 *
 * @author Mike Bostock
 * @since 1.0
 */

/**
 * A collection that supports order-independent equality, like {@link Set}, but may have duplicate
 * elements. A multiset is also sometimes called a <i>bag</i>.
 *
 * <p>Elements of a multiset that are equal to one another are referred to as <i>occurrences</i> of
 * the same single element. The total number of occurrences of an element in a multiset is called
 * the <i>count</i> of that element (the terms "frequency" and "multiplicity" are equivalent, but

   *
   * <pre>{@code
   * final class DirectExecutor implements Executor {
   *   public void execute(Runnable r) {
   *     r.run();
   *   }
   * }
   * }</pre>
   *
   * <p>This should be preferred to {@link #newDirectExecutorService()} because implementing the
   * {@link ExecutorService} subinterface necessitates significant performance overhead.
   *
   * @since 18.0
   */

@ElementTypesAreNonnullByDefault
final class Platform {
  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>
      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
    return CompactHashMap.createWithExpectedSize(expectedSize);
  }

  /**
   * Returns the platform preferred implementation of an insertion ordered map based on a hash
   * table.
   */

  // execution significantly)

  /**
   * This classloader disallows {@link sun.misc.Unsafe}, which will prevent us from selecting our
   * preferred strategy {@code UnsafeAtomicHelper}.
   */
  private static final ClassLoader NO_UNSAFE =
      getClassLoader(ImmutableSet.of(sun.misc.Unsafe.class.getName()));

  /**

   * write operations. Expired entries are cleaned up as part of the routine maintenance described
   * in the class javadoc.
   *
   * <p>If you can represent the duration as a {@link java.time.Duration} (which should be preferred
   * when feasible), use {@link #expireAfterWrite(Duration)} instead.
   *
   * @param duration the length of time after an entry is created that it should be automatically
   *     removed

   * the path {@code a/../b}, which {@code simplifyPath} will change to {@code b}. If {@code a} is a
   * symlink to {@code x}, {@code a/../b} may refer to a sibling of {@code x}, rather than the
   * sibling of {@code a} referred to by {@code b}.
   *
   * @since 11.0
   */
  public static String simplifyPath(String pathname) {
    checkNotNull(pathname);
    if (pathname.length() == 0) {
      return ".";
    }

  /**
   * Start of Heading: A communication control character used at the beginning of a sequence of
   * characters which constitute a machine-sensible address or routing information. Such a sequence
   * is referred to as the "heading." An STX character has the effect of terminating a heading.
   *
   * @since 8.0
   */
  public static final byte SOH = 1;

  /**

  // http://docs.oracle.com/javase/6/docs/technotes/guides/security/crypto/CryptoSpec.html
  //  - Some providers may choose to also include alias names.
  //  - For example, the "SHA-1" algorithm might be referred to as "SHA1".
  //  - The algorithm name is not case-sensitive.
  private static final ImmutableMap<String, HashFunction> ALGORITHMS =
      new ImmutableMap.Builder<String, HashFunction>()
          .put("MD5", Hashing.md5())