import com.google.j2objc.annotations.J2ObjCIncompatible;
import java.time.Duration;
import java.util.concurrent.TimeUnit;

/**
 * An object that accurately measures <i>elapsed time</i>: the measured duration between two
 * successive readings of "now" in the same process.
 *
 * <p>In contrast, <i>wall time</i> is a reading of "now" as given by a method like
 * {@link System#currentTimeMillis()}, best represented as an {@link java.time.Instant}. Such values