// We do this instead of Preconditions.checkNotNull to save boxing and array
  // creation cost.
  @CanIgnoreReturnValue
  static Object checkElementNotNull(Object element, int index) {
    if (element == null) {
      throw new NullPointerException("at index " + index);
    }
    return element;
  }

   *
   * Map<String, Color> colorForName = allColors.uniqueIndex(toStringFunction());
   * assertThat(colorForName).containsEntry("red", red);
   * }</pre>
   *
   * <p>If your index may associate multiple values with each key, use {@link #index(Function)
   * index}.
   *
   * <p><b>{@code Stream} equivalent:</b> use {@code
   * stream.collect(ImmutableMap.toImmutableMap(keyFunction, v -> v))}. {@code

    ImmutableListMultimap<Integer, String> index =
        FluentIterable.from(asList("one", "two", "three", "four"))
            .index(
                new Function<String, Integer>() {
                  @Override
                  public Integer apply(String input) {
                    return input.length();
                  }
                });
    assertEquals(expected, index);
  }

				if len(fromCallbacks) > 0 {
					for i := 0; i < stmt.ReflectValue.Len(); i++ {
						stmt.AddError(field.Set(stmt.Context, stmt.ReflectValue.Index(i), value))
					}
				} else {
					stmt.AddError(field.Set(stmt.Context, stmt.ReflectValue.Index(stmt.CurDestIndex), value))
				}
			case reflect.Struct:
				if !stmt.ReflectValue.CanAddr() {
					stmt.AddError(ErrInvalidValue)
					return
				}

{
  "index": {
    "refresh_interval": "1s",
    "number_of_shards": 1,
    "number_of_replicas": 0,
    "auto_expand_replicas": "0-1"
  }

{
  "settings": {
    "index": {
      "refresh_interval": "1s",
      "number_of_shards": 1,
      "number_of_replicas": 0,
      "auto_expand_replicas": "0-1"
    }
  }

{
  "settings": {
    "index": {
      "refresh_interval": "1s",
      "number_of_shards": 1,
      "number_of_replicas": 0,
      "auto_expand_replicas": "0-1"
    }
  }

{
  "settings": {
    "index": {
      "refresh_interval": "1s",
      "number_of_shards": 1,
      "number_of_replicas": 0,
      "auto_expand_replicas": "0-1"
    }
  }

{
  "settings": {
    "index": {
      "refresh_interval": "1s",
      "number_of_shards": 1,
      "number_of_replicas": 0,
      "auto_expand_replicas": "0-1"
    }
  }

{
  "settings": {
    "index": {
      "refresh_interval": "1s",
      "number_of_shards": 1,
      "number_of_replicas": 0,
      "auto_expand_replicas": "0-1"
    }
  }