};

  private final NavigableMap<K, V> delegate;

  public SafeTreeMap() {
    this(new TreeMap<K, V>());
  }

  public SafeTreeMap(Comparator<? super K> comparator) {
    this(new TreeMap<K, V>(comparator));
  }

  public SafeTreeMap(Map<? extends K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

  public SafeTreeMap(SortedMap<K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

      };

  private final NavigableMap<K, V> delegate;

  public SafeTreeMap() {
    this(new TreeMap<K, V>());
  }

  public SafeTreeMap(Comparator<? super K> comparator) {
    this(new TreeMap<K, V>(comparator));
  }

  public SafeTreeMap(Map<? extends K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

  public SafeTreeMap(SortedMap<K, ? extends V> map) {
    this(new TreeMap<K, V>(map));
  }

import com.google.common.collect.Synchronized.SynchronizedSortedMap;
import com.google.common.collect.testing.NavigableMapTestSuiteBuilder;
import com.google.common.collect.testing.SafeTreeMap;
import com.google.common.collect.testing.TestStringSortedMapGenerator;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;

                    for (Entry<String, String> entry : entries) {
                      map.put(entry.getKey(), entry.getValue());
                    }
                    return new StandardImplForwardingNavigableMap<>(map);
                  }
                })
            .named(
                "ForwardingNavigableMap[SafeTreeMap] with no comparator and standard "