unfiltered.put("apple", 2);
    unfiltered.put("banana", 6);
    unfiltered.put("cat", 4);
    unfiltered.put("dog", 3);
    SortedMap<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);

    assertEquals(ImmutableMap.of("banana", 6), filtered.headMap("dog"));
    assertEquals(ImmutableMap.of(), filtered.headMap("banana"));
    assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.headMap("emu"));

                    NavigableMap<String, String> map = new SafeTreeMap<>();
                    putEntries(map, entries);
                    map.put("banana", "toast");
                    map.put("eggplant", "spam");
                    return Maps.filterKeys(map, FILTER_KEYS);
                  }
                })

    unfiltered.put("apple", 2);
    unfiltered.put("banana", 6);
    unfiltered.put("cat", 4);
    unfiltered.put("dog", 3);
    SortedMap<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);

    assertEquals(ImmutableMap.of("banana", 6), filtered.headMap("dog"));
    assertEquals(ImmutableMap.of(), filtered.headMap("banana"));
    assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.headMap("emu"));

  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<String, Integer, String> table = HashBasedTable.create();
    table.put("foo", 1, "apple");
    table.put("bar", 1, "banana");
    table.put("foo", 3, "cat");
    return Tables.transformValues(table, TableCollectionTest.FIRST_CHARACTER).rowMap();
  }

   * are broken arbitrarily.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Stream.of("foo", "quux", "banana", "elephant")
   *     .collect(greatest(2, comparingInt(String::length)))
   * // returns {"elephant", "banana"}
   * }</pre>
   *
   * <p>This {@code Collector} uses O(k) memory and takes expected time O(n) (worst-case O(n log

                  @Override
                  public SampleElements<Entry<Range<Integer>, String>> samples() {
                    return new SampleElements<>(
                        mapEntry(Range.singleton(0), "banana"),
                        mapEntry(Range.closedOpen(3, 5), "frisbee"),
                        mapEntry(Range.atMost(-1), "fruitcake"),
                        mapEntry(Range.open(10, 15), "elephant"),

   * are broken arbitrarily.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Stream.of("foo", "quux", "banana", "elephant")
   *     .collect(greatest(2, comparingInt(String::length)))
   * // returns {"elephant", "banana"}
   * }</pre>
   *
   * <p>This {@code Collector} uses O(k) memory and takes expected time O(n) (worst-case O(n log

  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<Integer, String, String> table = HashBasedTable.create();
    table.put(1, "foo", "apple");
    table.put(1, "bar", "banana");
    table.put(3, "foo", "cat");
    return Tables.transformValues(table, FIRST_CHARACTER).columnMap();
  }

                    NavigableMap<String, String> map = new SafeTreeMap<>();
                    putEntries(map, entries);
                    map.put("banana", "toast");
                    map.put("eggplant", "spam");
                    return Maps.filterKeys(map, FILTER_KEYS);
                  }
                })

  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<Integer, String, String> table = HashBasedTable.create();
    table.put(1, "foo", "apple");
    table.put(1, "bar", "banana");
    table.put(3, "foo", "cat");
    return Tables.transformValues(table, FIRST_CHARACTER).columnMap();
  }