this.allowsNullKeys = allowsNullKeys;
    this.allowsNullValues = allowsNullValues;
    this.supportsIteratorRemove = supportsIteratorRemove;
  }

  /**
   * Used by tests that require a map, but don't care whether it's populated or not.
   *
   * @return a new map instance.
   */
  protected Map<K, V> makeEitherMap() {
    try {
      return makePopulatedMap();

   * 0}.
   *
   * @throws IllegalArgumentException if {@code a < 0} or {@code b < 0}
   */
  public static long gcd(long a, long b) {
    /*
     * The reason we require both arguments to be >= 0 is because otherwise, what do you return on
     * gcd(0, Long.MIN_VALUE)? BigInteger.gcd would return positive 2^63, but positive 2^63 isn't an
     * int.
     */
    checkNonNegative("a", a);

  /**
   * Runs Runnable r with a security policy that permits precisely the specified permissions. If
   * there is no current security manager, the runnable is run twice, both with and without a
   * security manager. We require that any security manager permit getPolicy/setPolicy.
   */
  public void runWithPermissions(Runnable r, Permission... permissions) {
    SecurityManager sm = System.getSecurityManager();
    if (sm == null) {

 * supertype of `Function<A, B>` turns out to be massively more useful to callers in practice: They
 * want their output to be non-null in operations like `stream.map(myConverter)`, and we can
 * guarantee that as long as we also require the input type to be non-null[*] (which is a
 * requirement that existing callers already fulfill).
 *
 * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that

      // extra zero bits we need to add to the end of bitsPerChar to get 3 in total.
      // The logic here would be wrong for bitsPerChar > 8, but since we require distinct ASCII
      // characters that can't happen.
      int zeroesInBitsPerChar = Integer.numberOfTrailingZeros(bitsPerChar);
      this.charsPerChunk = 1 << (3 - zeroesInBitsPerChar);

    byte[] b = ByteStreams.toByteArray(in);
    assertThat(b).isEqualTo(new byte[0]);
  }

  public void testToByteArray_largeStream() throws IOException {
    // well, large enough to require multiple buffers
    byte[] expected = newPreFilledByteArray(10000000);
    InputStream in = new ByteArrayInputStream(expected);
    byte[] b = ByteStreams.toByteArray(in);
    assertThat(b).isEqualTo(expected);
  }

      return true;
    }
    // This falls into the undirected A->B->A case. The Graph interface does not support parallel
    // edges, so this traversal would require reusing the undirected AB edge.
    return false;
  }

  /**
   * Returns the transitive closure of {@code graph}. The transitive closure of a graph is another

  }

  /**
   * Returns true if the given member is a method that overrides {@link Object#equals(Object)}.
   *
   * <p>The documentation for {@link Object#equals} says it should accept null, so don't require an
   * explicit {@code @NullableDecl} annotation (see <a
   * href="https://github.com/google/guava/issues/1819">#1819</a>).
   *

  }

  /**
   * Returns true if the given member is a method that overrides {@link Object#equals(Object)}.
   *
   * <p>The documentation for {@link Object#equals} says it should accept null, so don't require an
   * explicit {@code @Nullable} annotation (see <a
   * href="https://github.com/google/guava/issues/1819">#1819</a>).
   *

   * reconstructed using public factory methods. This ensures that the implementation types remain
   * as implementation details.
   *
   * <p>Since the bimap is immutable, ImmutableBiMap doesn't require special logic for keeping the
   * bimap and its inverse in sync during serialization, the way AbstractBiMap does.
   */
  @J2ktIncompatible // serialization