Map<String, String> transformed = transformEntries(map, concat);

    assertEquals(ImmutableMap.of("a", "a4", "b", "b9"), transformed);
  }

  @SuppressWarnings("unused")
  public void testTransformEntriesGenerics() {
    Map<Object, Object> map1 = ImmutableMap.<Object, Object>of(1, 2);
    Map<Object, Number> map2 = ImmutableMap.<Object, Number>of(1, 2);
    Map<Object, Integer> map3 = ImmutableMap.<Object, Integer>of(1, 2);

    Map<String, String> transformed = transformEntries(map, concat);

    assertEquals(ImmutableMap.of("a", "a4", "b", "b9"), transformed);
  }

  @SuppressWarnings("unused")
  public void testTransformEntriesGenerics() {
    Map<Object, Object> map1 = ImmutableMap.<Object, Object>of(1, 2);
    Map<Object, Number> map2 = ImmutableMap.<Object, Number>of(1, 2);
    Map<Object, Integer> map3 = ImmutableMap.<Object, Integer>of(1, 2);