void testSingletonInstance() {
        MonotonicClock clock1 = MonotonicClock.get();
        MonotonicClock clock2 = MonotonicClock.get();

        assertSame(clock1, clock2, "Multiple calls to get() should return the same instance");
    }

    @Test
    @DisplayName("MonotonicClock should always use UTC timezone")
    void testClockTimezone() {
        MonotonicClock clock = MonotonicClock.get();

import com.google.common.annotations.GwtCompatible;
import java.util.Collection;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A set which forwards all its method calls to another set. Subclasses should override one or more
 * methods to modify the behavior of the backing set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

 *
 * <p>The multimap constructor takes a map that has a single entry for each distinct key. When you
 * insert a key-value pair with a key that isn't already in the multimap, {@code
 * AbstractMapBasedMultimap} calls {@link #createCollection()} to create the collection of values
 * for that key. The subclass should not call {@link #createCollection()} directly, and a new
 * instance should be created every time the method is called.
 *

///

## Other Asynchronous Function Calls { #other-asynchronous-function-calls }

    intend to ship a public API for these features, but we don't want to hold OkHttp 5.0.0 until
    those APIs are stable.

 *  Fix: Change `MockWebServer.close()` to cancel ongoing calls that are blocked on a delay.

 *  Upgrade: [Okio 3.13.0][okio_3_13_0].

This release also stabilizes many APIs in the `mockwebserver3` artifact that's new in 5.0.

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Deque;
import java.util.Iterator;
import org.jspecify.annotations.Nullable;

/**
 * A deque which forwards all its method calls to another deque. Subclasses should override one or
 * more methods to modify the behavior of the backing deque as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

 *        * body ([responseBodyStart], [responseBodyEnd])
 *
 * This nesting is typical but not strict. For example, when calls use "Expect: continue" the
 * request body start and end events occur within the response header events. Similarly,
 * [duplex calls][RequestBody.isDuplex] interleave the request and response bodies.
 *

/**
 * Imposes a time limit on method calls.
 *
 * @author Kevin Bourrillion
 * @author Jens Nyman
 * @since 1.0
 */
@DoNotMock("Use FakeTimeLimiter")
@J2ktIncompatible
@GwtIncompatible
@SuppressWarnings("GoodTime") // should have java.time.Duration overloads
public interface TimeLimiter {

  /**
   * Returns an instance of {@code interfaceType} that delegates all method calls to the {@code

/**
 * A listening executor service which forwards all its method calls to another listening executor
 * service. Subclasses should override one or more methods to modify the behavior of the backing
 * executor service as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code

  override fun proceed(request: Request): Response {
    check(index < interceptors.size)

    calls++

    if (exchange != null) {
      check(exchange.finder.routePlanner.sameHostAndPort(request.url)) {
        "network interceptor ${interceptors[index - 1]} must retain the same host and port"
      }
      check(calls == 1) {
        "network interceptor ${interceptors[index - 1]} must call proceed() exactly once"
      }