* See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.Sets.unmodifiableNavigableSet;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multisets.UnmodifiableMultiset;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.util.Comparator;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.Sets.unmodifiableNavigableSet;
import static java.util.Collections.unmodifiableSortedSet;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;

      return set;
    }
    return new UnmodifiableNavigableSet<>(set);
  }

  static final class UnmodifiableNavigableSet<E extends @Nullable Object>
      extends ForwardingSortedSet<E> implements NavigableSet<E>, Serializable {
    private final NavigableSet<E> delegate;
    private final SortedSet<E> unmodifiableDelegate;

    UnmodifiableNavigableSet(NavigableSet<E> delegate) {

                NavigableSet<String> innerSet = new TreeSet<>();
                Collections.addAll(innerSet, elements);
                return Collections.unmodifiableNavigableSet(innerSet);
              }
            })
        .named("unmodifiableNavigableSet/TreeSet, natural")
        .withFeatures(
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.RESTRICTS_ELEMENTS,

                    return unmodifiableNavigableSet(set);
                  }

                  @Override
                  public List<String> order(List<String> insertionOrder) {
                    return Ordering.natural().sortedCopy(insertionOrder);
                  }
                })
            .named("Sets.unmodifiableNavigableSet[TreeSet]")
            .withFeatures(

          .put(ImmutableSet.class, ImmutableSet.of())
          .put(SortedSet.class, ImmutableSortedSet.of())
          .put(ImmutableSortedSet.class, ImmutableSortedSet.of())
          .put(NavigableSet.class, Sets.unmodifiableNavigableSet(Sets.newTreeSet()))
          .put(Map.class, ImmutableMap.of())
          .put(ImmutableMap.class, ImmutableMap.of())
          .put(SortedMap.class, ImmutableSortedMap.of())

          .put(ImmutableSet.class, ImmutableSet.of())
          .put(SortedSet.class, ImmutableSortedSet.of())
          .put(ImmutableSortedSet.class, ImmutableSortedSet.of())
          .put(NavigableSet.class, Sets.unmodifiableNavigableSet(Sets.newTreeSet()))
          .put(Map.class, ImmutableMap.of())
          .put(ImmutableMap.class, ImmutableMap.of())
          .put(SortedMap.class, ImmutableSortedMap.of())

    }

    @Override
    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
        Collection<E> collection) {
      if (collection instanceof NavigableSet) {
        return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
      } else if (collection instanceof SortedSet) {
        return Collections.unmodifiableSortedSet((SortedSet<E>) collection);
      } else if (collection instanceof Set) {

      return navigableKeySet();
    }

    @Override
    public NavigableSet<K> navigableKeySet() {
      return Sets.unmodifiableNavigableSet(delegate.navigableKeySet());
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return Sets.unmodifiableNavigableSet(delegate.descendingKeySet());
    }

    @Override

      return navigableKeySet();
    }

    @Override
    public NavigableSet<K> navigableKeySet() {
      return Sets.unmodifiableNavigableSet(delegate.navigableKeySet());
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return Sets.unmodifiableNavigableSet(delegate.descendingKeySet());
    }

    @Override