private MinimalIterable(Iterator<E> iterator) {
    this.iterator = iterator;
  }

  @Override
  public Iterator<E> iterator() {
    if (iterator == null) {
      // TODO: throw something else? Do we worry that people's code and tests
      // might be relying on this particular type of exception?
      throw new IllegalStateException();
    }
    try {
      return iterator;
    } finally {
      iterator = null;

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## Recap { #recap }

Declare headers with `Header`, using the same common pattern as `Query`, `Path` and `Cookie`.

  private MinimalIterable(Iterator<E> iterator) {
    this.iterator = iterator;
  }

  @Override
  public Iterator<E> iterator() {
    if (iterator == null) {
      // TODO: throw something else? Do we worry that people's code and tests
      // might be relying on this particular type of exception?
      throw new IllegalStateException();
    }
    try {
      return iterator;
    } finally {
      iterator = null;

            throw new GraphConflictResolutionException("graph with an entry, but not vertices do not exist");
        }

        if (graph.isEmptyEdges()) {
            return null; // no edges - nothing to worry about
        }

        final TreeSet<MetadataGraphVertex> vertices = graph.getVertices();

        try {
            // edge case - single vertex graph
            if (vertices.size() == 1) {

Because each JSON object will be separated by a new line, they can't contain literal new line characters in their content, but they can contain escaped new lines (`\n`), which is part of the JSON standard.

But normally you won't have to worry about it, it's done automatically, continue reading. 🤓

///

## Use Cases { #use-cases }

    @Override
    public @Nullable Class<?> loadFinalizer() {
      if (disabled) {
        return null;
      }
      if (isAndroid()) {
        // We need not worry about class unloading under Android. Plus, this approach wouldn't work.
        return null;
      }
      ClassLoader systemLoader;
      try {
        systemLoader = ClassLoader.getSystemClassLoader();

    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();
    Reader reader = concatenated.openStream(); // no need to worry about closing
    for (int i = 0; i < 8; i++) {
      builder.append((char) reader.read());
    }
    assertThat(builder.toString()).isEqualTo(expected);
  }

<img src="/img/tutorial/body-nested-models/image01.png">

You couldn't get this kind of editor support if you were working directly with `dict` instead of Pydantic models.

But you don't have to worry about them either, incoming dicts are converted automatically and your output is converted automatically to JSON too.

## Bodies of arbitrary `dict`s { #bodies-of-arbitrary-dicts }

/// tip

Don't worry if some of these items about **containers**, Docker, or Kubernetes don't make a lot of sense yet.

I'll tell you more about container images, Docker, Kubernetes, etc. in a future chapter: [FastAPI in Containers - Docker](docker.md).

      throw new AssertionError(e);
    }
  }

  private static @Nullable Field getInheritableThreadLocalsField() {
    if (isAndroid()) {
      /*
       * We need not worry about class unloading under Android. Plus, this approach doesn't always
       * work under Android.
       *
       * (Clearing inheritableThreadLocals could still be useful independent of class unloading, but