@Override
    public NavigableMap<K, V> descendingMap() {
      return new StandardDescendingMap();
    }

    @Override
    public NavigableSet<K> navigableKeySet() {
      return new StandardNavigableKeySet();
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return standardDescendingKeySet();
    }

    @Override
    public K firstKey() {
      return standardFirstKey();

  @Override
  int indexOf(@Nullable Object target) {
    return -1;
  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return emptyIterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return emptyIterator();
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override

      List<String> list = Lists.newArrayList(elements);
      list.add("\0");
      list.add("zzz");
      return ImmutableSortedSet.copyOf(list).subSet("\0\0", "zzy");
    }
  }

  @GwtIncompatible // NavigableSet
  public static class ImmutableSortedSetDescendingGenerator extends TestStringSortedSetGenerator {
    @Override
    protected SortedSet<String> create(String[] elements) {

import com.google.common.testing.EqualsTester;
import com.google.common.testing.ForwardingWrapperTester;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NavigableSet;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**

    @Override
    public NavigableMap<K, V> descendingMap() {
      return new StandardDescendingMap();
    }

    @Override
    public NavigableSet<K> navigableKeySet() {
      return new StandardNavigableKeySet();
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return standardDescendingKeySet();
    }

    @Override
    public K firstKey() {
      return standardFirstKey();

import com.google.common.testing.EqualsTester;
import com.google.common.testing.ForwardingWrapperTester;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NavigableSet;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**

    suite.addTest(
        NavigableSetTestSuiteBuilder.using(
                new TestStringSetGenerator() {
                  @Override
                  public NavigableSet<String> create(String[] elements) {
                    NavigableSet<String> unfiltered = Sets.newTreeSet();
                    unfiltered.add("yyy");
                    unfiltered.addAll(ImmutableList.copyOf(elements));

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.SortedSet;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * A {@link NavigableSet} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *

package com.google.common.collect;

import static com.google.common.collect.Maps.keyOrNull;

import com.google.common.annotations.GwtIncompatible;
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import org.jspecify.annotations.Nullable;

/**
 * A navigable map which forwards all its method calls to another navigable map. Subclasses should

package com.google.common.collect;

import static com.google.common.collect.Maps.keyOrNull;

import com.google.common.annotations.GwtIncompatible;
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import java.util.function.BiFunction;
import org.jspecify.annotations.Nullable;

/**