/// note

Notice that, in this case, the `item` that would be taken from the body is optional. As it has a `None` default value.

///

## Multiple body parameters { #multiple-body-parameters }

In the previous example, the *path operations* would expect a JSON body with the attributes of an `Item`, like:

```JSON
{
    "name": "Foo",

        });
    assertThat(orig.toString())
        .contains("Exception thrown from implementation: class java.lang.StackOverflowError");
  }

  // Regression test for a case where we would fail to execute listeners immediately on done futures
  // this would be observable from an afterDone callback
  public void testListenersExecuteImmediately_fromAfterDone() {
    AbstractFuture<String> f =
        new AbstractFuture<String>() {

* `upgrade`: Upgrades

 * such custom interfaces directly; they are implemented only in subclasses. Therefore, forwarding
 * {@code equals} would break symmetry, as the forwarding object might consider itself equal to the
 * object being tested, but the reverse could not be true. This behavior is consistent with the
 * JDK's collection wrappers, such as {@link java.util.Collections#unmodifiableCollection}. Use an

It might also help avoid confusion for new developers that see an unused parameter in your code and could think it's unnecessary.

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md).

///

* [`@contextlib.asynccontextmanager`](https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager)

would be valid to use as a **FastAPI** dependency.

In fact, FastAPI uses those two decorators internally.

///

## A database dependency with `yield` { #a-database-dependency-with-yield }

For example, you could use this to create a database session and close it after finishing.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

That way, the sub-application will know to use that path prefix for the docs UI.

And the sub-application could also have its own mounted sub-applications and everything would work correctly, because FastAPI handles all these `root_path`s automatically.

            <configuration>
              <excludes>
                <!-- Yes, we want to exclude ForceGuavaCompilation 4 times: -->
                <!-- (And we might as well exclude DummyJavadocClass 3 times (though it would be harmless to include).) -->
                <!-- 1. Don't compile it (since that requires a *non-test* dep on gwt-user. -->
                <exclude>**/ForceGuavaCompilation*</exclude>

   * to stop requests. You could poll for lifecycle changes in a work loop:
   *
   * <pre>
   *   public void run() {
   *     while ({@link #isRunning()}) {
   *       // perform a unit of work
   *     }
   *   }
   * </pre>
   *
   * <p>...or you could respond to stop requests by implementing {@link #triggerShutdown()}, which