SortedMap<String, Integer> map = sortedNotNavigable(ImmutableSortedMap.of("a", 4, "b", 9));
    SortedMap<String, Double> transformed = transformValues(map, SQRT_FUNCTION);

    /*
     * We'd like to sanity check that we didn't get a NavigableMap out, but we
     * can't easily do so while maintaining GWT compatibility.
     */
    assertEquals(ImmutableSortedMap.of("a", 2.0, "b", 3.0), transformed);
  }

    SortedMap<String, Integer> map = sortedNotNavigable(ImmutableSortedMap.of("a", 4, "b", 9));
    SortedMap<String, Double> transformed = transformValues(map, SQRT_FUNCTION);

    /*
     * We'd like to sanity check that we didn't get a NavigableMap out, but we
     * can't easily do so while maintaining GWT compatibility.
     */
    assertEquals(ImmutableSortedMap.of("a", 2.0, "b", 3.0), transformed);
  }