int h2 = Objects.hashCode(Integer.valueOf(1), new String("two"), Double.valueOf(3.0));
    // repeatable
    assertEquals(h1, h2);

    // These don't strictly need to be true, but they're nice properties.
    assertTrue(Objects.hashCode(1, 2, null) != Objects.hashCode(1, 2));
    assertTrue(Objects.hashCode(1, 2, null) != Objects.hashCode(1, null, 2));
    assertTrue(Objects.hashCode(1, null, 2) != Objects.hashCode(1, 2));

    Function<Float, Boolean> c1 = Functions.compose(Functions.compose(h, g), f);
    Function<Float, Boolean> c2 = Functions.compose(h, Functions.compose(g, f));

    // Might be nice (eventually) to have:
    //     assertEquals(c1, c2);

    // But for now, settle for this:
    assertEquals(c1.hashCode(), c2.hashCode());

    assertEquals(c1.apply(1.0f), c2.apply(1.0f));

/// info

Keep in mind that dataclasses can't do everything Pydantic models can do.

So, you might still need to use Pydantic models.

But if you have a bunch of dataclasses laying around, this is a nice trick to use them to power a web API using FastAPI. 🤓

///

## Dataclasses in `response_model` { #dataclasses-in-response-model }

You can also use `dataclasses` in the `response_model` parameter:

class by appending the class name to guava.dev. For example,
[guava.dev/ImmutableList](https://guava.dev/ImmutableList)!

## Learn about Guava

-   Our users' guide, [Guava Explained]
-   [A nice collection](https://www.tfnico.com/presentations/google-guava) of
    other helpful links

## Links

-   [GitHub project](https://github.com/google/guava)

    Function<Float, Boolean> c1 = Functions.compose(Functions.compose(h, g), f);
    Function<Float, Boolean> c2 = Functions.compose(h, Functions.compose(g, f));

    // Might be nice (eventually) to have:
    //     assertEquals(c1, c2);

    // But for now, settle for this:
    assertEquals(c1.hashCode(), c2.hashCode());

    assertEquals(c1.apply(1.0f), c2.apply(1.0f));

| `minio_node_cpu_avg_iowait_max`      | CPU ioWait time (max).                     |
| `minio_node_cpu_avg_nice`            | CPU nice time.                             |
| `minio_node_cpu_avg_nice_avg`        | CPU nice time (avg).                       |
| `minio_node_cpu_avg_nice_max`        | CPU nice time (max).                       |
| `minio_node_cpu_avg_steal`           | CPU steam time.                            |

   * `new Integer` (as we do) instead of `Integer.valueOf`. However, under J2KT, `new Integer`
   * gets translated back to `Integer.valueOf` because that is the only thing J2KT can support. And
   * anyway, it's nice to avoid `Integer.valueOf` because the Android toolchain optimizes multiple
   * `Integer.valueOf` calls into one! So we stick with the deprecated `Integer` constructor.
   */

  public void testEqualsEquivalent() {

   * `new Integer` (as we do) instead of `Integer.valueOf`. However, under J2KT, `new Integer`
   * gets translated back to `Integer.valueOf` because that is the only thing J2KT can support. And
   * anyway, it's nice to avoid `Integer.valueOf` because the Android toolchain optimizes multiple
   * `Integer.valueOf` calls into one! So we stick with the deprecated `Integer` constructor.
   */

  public void testEqualsEquivalent() {

      // platforms in order to support Robolectric, which mixes classes from both Android and the
      // Oracle JDK. Note that we don't support HTTP/2 or other nice features on Robolectric.
      val sslContextClass = Class.forName("sun.security.ssl.SSLContextImpl")
      val context = readFieldOrNull(sslSocketFactory, sslContextClass, "context") ?: return null

With just that Python type declaration, **FastAPI** will:

* Read the body of the request as JSON.
* Convert the corresponding types (if needed).
* Validate the data.
    * If the data is invalid, it will return a nice and clear error, indicating exactly where and what was the incorrect data.
* Give you the received data in the parameter `item`.