return standardSubSet(fromElement, toElement);
    }

    @Override
    public @Nullable T lower(T e) {
      return standardLower(e);
    }

    @Override
    public @Nullable T floor(T e) {
      return standardFloor(e);
    }

    @Override
    public @Nullable T ceiling(T e) {
      return standardCeiling(e);
    }

    @Override
    public @Nullable T higher(T e) {

/**
 * Benchmarks for the rounding methods of {@code LongMath}.
 *
 * @author Louis Wasserman
 */
@NullUnmarked
public class LongMathRoundingBenchmark {
  @Param({"DOWN", "UP", "FLOOR", "CEILING", "HALF_EVEN", "HALF_UP", "HALF_DOWN"})
  RoundingMode mode;

  private static final long[] positive = new long[ARRAY_SIZE];
  private static final long[] nonzero = new long[ARRAY_SIZE];

    assertThat(set.floor("f")).isNull();
  }

  public void testFloor_elementPresent() {
    ImmutableSortedSet<String> set =
        ImmutableSortedSet.copyOf(new String[] {"e", "a", "e", "f", "b", "i", "d", "a", "c", "k"});
    assertThat(set.floor("f")).isEqualTo("f");
    assertThat(set.floor("j")).isEqualTo("i");
    assertThat(set.floor("q")).isEqualTo("k");
  }

  }

  @Override
  public @Nullable E lower(E element) {
    int index = headIndex(element, false) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E ceiling(E element) {

  static double bigToDouble(BigInteger x) {
    // This is an extremely fast implementation of BigInteger.doubleValue(). JDK patch pending.
    BigInteger absX = x.abs();
    int exponent = absX.bitLength() - 1;
    // exponent == floor(log2(abs(x)))
    if (exponent < Long.SIZE - 1) {
      return x.longValue();
    } else if (exponent > MAX_EXPONENT) {
      return x.signum() * POSITIVE_INFINITY;
    }

    /*

    private @Nullable AvlNode<E> floor(Comparator<? super E> comparator, @ParametricNullness E e) {
      int cmp = comparator.compare(e, getElement());
      if (cmp > 0) {
        return (right == null) ? this : MoreObjects.firstNonNull(right.floor(comparator, e), this);
      } else if (cmp == 0) {
        return this;
      } else {
        return (left == null) ? null : left.floor(comparator, e);
      }
    }

    }

    @Override
    public @Nullable V lower(@ParametricNullness V v) {
      return getSortedSetDelegate().lower(v);
    }

    @Override
    public @Nullable V floor(@ParametricNullness V v) {
      return getSortedSetDelegate().floor(v);
    }

    @Override
    public @Nullable V ceiling(@ParametricNullness V v) {
      return getSortedSetDelegate().ceiling(v);
    }

    @Override

    }

    @Override
    public @Nullable E lower(@ParametricNullness E e) {
      return delegate.lower(e);
    }

    @Override
    public @Nullable E floor(@ParametricNullness E e) {
      return delegate.floor(e);
    }

    @Override
    public @Nullable E ceiling(@ParametricNullness E e) {
      return delegate.ceiling(e);
    }

    @Override

                  GNU LESSER GENERAL PUBLIC LICENSE
                       Version 2.1, February 1999

 Copyright (C) 1991, 1999 Free Software Foundation, Inc.
 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

(This is the first released version of the Lesser GPL.  It also counts

   * simultaneously adopted and removed.
   */
  private val connections = ConcurrentLinkedQueue<RealConnection>()

  init {
    // Put a floor on the keep alive duration, otherwise cleanup will spin loop.
    require(keepAliveDuration > 0L) { "keepAliveDuration <= 0: $keepAliveDuration" }
  }

  fun idleConnectionCount(): Int =
    connections.count {