@CanIgnoreReturnValue
  public ForwardingWrapperTester includingEquals() {
    this.testsEquals = true;
    return this;
  }

  /**
   * Tests that the forwarding wrapper returned by {@code wrapperFunction} properly forwards method
   * calls with parameters passed as is, return value returned as is, and exceptions propagated as
   * is.
   */
  public <T> void testForwarding(

import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import org.jspecify.annotations.Nullable;

/**
 * A sorted map which forwards all its method calls to another sorted map. Subclasses should
 * override one or more methods to modify the behavior of the backing sorted map as desired per the

import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/**
 * An executor service which forwards all its method calls to another executor service. Subclasses
 * should override one or more methods to modify the behavior of the backing executor service as

import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import org.jspecify.annotations.Nullable;

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.NoSuchElementException;
import java.util.Queue;
import org.jspecify.annotations.Nullable;

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

   */
  private static final SuccessorsFunction<Character> TWO_CYCLES_GRAPH =
      createDirectedGraph("ab", "ac", "bc", "cd", "da");

  /**
   * A tree-shaped graph that looks as follows (all edges are directed facing downwards):
   *
   * {@snippet :
   *        h
   *       /|\
   *      / | \
   *     /  |  \
   *    d   e   g
   *   /|\      |
   *  / | \     |
   * a  b  c    f
   * }
   */

import java.util.Collection;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.TimeUnit;
import org.jspecify.annotations.Nullable;

/**
 * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
 * Subclasses should override one or more methods to modify the behavior of the backing deque as

import java.util.Collection;
import java.util.Iterator;
import java.util.Objects;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A multiset which forwards all its method calls to another multiset. Subclasses should override
 * one or more methods to modify the behavior of the backing multiset as desired per the <a

        public boolean reportProblem(P problem) {
            requireNonNull(problem, "problem");
            // first apply filter
            if (!filter.test(problem)) {
                // drop without counting towards preserved problems
                return false;
            }
            int currentCount = totalCount.incrementAndGet();
            getCounter(problem.getSeverity()).increment();

import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * A sorted set which forwards all its method calls to another sorted set. Subclasses should
 * override one or more methods to modify the behavior of the backing sorted set as desired per the