*/
public abstract class Converter<A, B> implements Function<A, B> {
  private final boolean handleNullAutomatically;

  // We lazily cache the reverse view to avoid allocating on every call to reverse().
  @LazyInit @RetainedWith @CheckForNull private transient Converter<B, A> reverse;

  /** Constructor for use by subclasses. */
  protected Converter() {
    this(true);
  }

  }

  /**
   * Returns the least value present in {@code array}.
   *
   * @param array a <i>nonempty</i> array of {@code int} values
   * @return the value present in {@code array} that is less than or equal to every other value in
   *     the array
   * @throws IllegalArgumentException if {@code array} is empty
   */
  @GwtIncompatible(
      "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.")

      }
    }
  }

  @GwtIncompatible // DoubleMath.roundToLong(double, RoundingMode)
  public void testRoundExactIntegralDoubleToLong() {
    for (double d : INTEGRAL_DOUBLE_CANDIDATES) {
      // every mode except UNNECESSARY
      BigDecimal expected = new BigDecimal(d).setScale(0, UNNECESSARY);
      boolean isInBounds =
          expected.compareTo(MAX_LONG_AS_BIG_DECIMAL) <= 0

      checkValidState(cache);
    }
  }

  /* ---------------- Local utilities -------------- */

  /** Most of the tests in this class run against every one of these caches. */
  private Iterable<LoadingCache<Object, Object>> caches() {
    // lots of different ways to configure a LoadingCache
    CacheBuilderFactory factory = cacheFactory();
    return Iterables.transform(

 * than {@code size()}. Furthermore, this structure only depends on a fixed number of arrays; {@code
 * add(x)} operations <i>do not</i> create objects for the garbage collector to deal with, and for
 * every element added, the garbage collector will have to traverse {@code 1.5} references on
 * average, in the marking phase, not {@code 5.0} as in {@code java.util.HashSet}.
 *

   */
  public static <T extends @Nullable Object> Predicate<T> in(Collection<? extends T> target) {
    return new InPredicate<>(target);
  }

  /**
   * Returns the composition of a function and a predicate. For every {@code x}, the generated
   * predicate returns {@code predicate(function(x))}.
   *
   * @return the composition of the provided function and predicate
   */

   * the underlying collection.
   *
   * <p>The returned collection isn't threadsafe or serializable, even if {@code unfiltered} is.
   *
   * <p>Many of the filtered collection's methods, such as {@code size()}, iterate across every
   * element in the underlying collection and determine which elements satisfy the filter. When a
   * live view is <i>not</i> needed, it may be faster to copy {@code Iterables.filter(unfiltered,
   * predicate)} and use the copy.

  private void assertEntrySetNotContainsString(Set<Entry<K, V>> entrySet) {
    // Very unlikely that a buggy collection would ever return true. It might accidentally throw.
    assertFalse(entrySet.contains("foo"));
  }

  /**
   * Override this to check invariants which should hold true for a particular implementation, but
   * which are not generally applicable to every instance of Map.
   *

  // value. In our example, it would be another entry for a key whose short hash is also 0x6f.
  //
  // Essentially, then, `table[h]` gives us the start of a linked list in `entries`, where every
  // element of the list has the short hash value h.
  //
  // A wrinkle here is that the value 0 (called UNSET in the code) is used as the equivalent of a

    Integer javaVersion = Ints.tryParse(JAVA_SPECIFICATION_VERSION.value());
    if (javaVersion != null && javaVersion >= 9) {
      return;
    }
    // Obviously this isn't guaranteed in every environment, but it works well enough for now:
    assertTrue(lazyStackTraceIsLazy());
  }

  @J2ktIncompatible
  @GwtIncompatible // lazyStackTrace(Throwable)
  public void testLazyStackTrace() {