import java.util.AbstractMap;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.SortedMap;
import java.util.Spliterator;
import java.util.TreeMap;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.Collector;

  ImmutableSortedSet<K> createKeySet() {
    // the keySet() of the delegate is only a Set and TreeMap.navigatableKeySet
    // is not available in GWT yet.  To keep the code simple and code size more,
    // we make a copy here, instead of creating a view of it.
    //
    // TODO: revisit if it's unbearably slow or when GWT supports
    // TreeMap.navigatbleKeySet().
    return ImmutableSortedSet.copyOf(comparator, sortedDelegate.keySet());
  }

import java.io.ObjectInputStream;
import java.util.AbstractMap;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import javax.annotation.CheckForNull;