assertEquals("d", itr2.next());
    assertEquals("c", itr2.next());
  }

  public void testConcatPartiallyAdvancedFirst() {
    Iterator<String> itr1 = Iterators.concat(singletonIterator("a"), Iterators.forArray("b", "c"));
    assertEquals("a", itr1.next());
    assertEquals("b", itr1.next());
    Iterator<String> itr2 = Iterators.concat(itr1, singletonIterator("d"));

    }
  }

  public void testConcat() {
    assertThat(Floats.concat()).isEqualTo(EMPTY);
    assertThat(Floats.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Floats.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Floats.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Floats.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Floats.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);

            implements ExtensibleEnumRegistry<T> {

        private final Map<String, T> values;

        DefaultExtensibleEnumRegistry(List<P> providers, T... builtinValues) {
            values = Stream.<T>concat(
                            Stream.of(builtinValues), providers.stream().flatMap(p -> p.provides().stream()))
                    .collect(Collectors.toMap(t -> t.id(), t -> t));
        }

        @Override

                    copyBeanToBean(entity, form, copyOp -> {
                        copyOp.excludeNull();
                        copyOp.exclude(Stream.concat(Stream.of(Constants.COMMON_CONVERSION_RULE),
                                Stream.of(Constants.PERMISSIONS, Constants.VIRTUAL_HOSTS)).toArray(n -> new String[n]));
                    });

                    copyBeanToBean(entity, form, copyOp -> {
                        copyOp.excludeNull();
                        copyOp.exclude(Stream.concat(Stream.of(Constants.COMMON_CONVERSION_RULE),
                                Stream.of(Constants.PERMISSIONS, Constants.VIRTUAL_HOSTS)).toArray(n -> new String[n]));
                    });

    assertEquals(asList(1, 4, 7, 8, 9, 10), newArrayList(result));
    assertEquals("[1, 4, 7, 8, 9, 10]", result.toString());
  }

  public void testConcatNullPointerException() {
    List<Integer> list1 = newArrayList(1);
    List<Integer> list2 = newArrayList(4);

    try {
      FluentIterable.concat(list1, null, list2);
      fail();

    assertThat(Ints.concat()).isEqualTo(EMPTY);
    assertThat(Ints.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Ints.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Ints.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Ints.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Ints.concat(ARRAY1, ARRAY1, ARRAY1))

    }
  }

  public void testConcat() {
    assertThat(Shorts.concat()).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Shorts.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Shorts.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Shorts.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);

    assertThat(Chars.concat()).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Chars.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1, ARRAY1, ARRAY1))

                    copyBeanToBean(entity, form, copyOp -> {
                        copyOp.excludeNull();
                        copyOp.exclude(Stream.concat(Stream.of(Constants.COMMON_CONVERSION_RULE),
                                Stream.of(Constants.PERMISSIONS, Constants.VIRTUAL_HOSTS)).toArray(n -> new String[n]));
                    });