User user1 = createTestUser("user1", "User One");
        User user2 = createTestUser("user2", "User Two");
        User result1 = createTestUser("result1", "Result One");
        User result2 = createTestUser("result2", "Result Two");

        chain.loadResult = result1;
        User returnedUser1 = chain.load(user1);

        chain.loadResult = result2;

# Sub Applications - Mounts { #sub-applications-mounts }

If you need to have two independent FastAPI applications, with their own independent OpenAPI and their own docs UIs, you can have a main app and "mount" one (or more) sub-application(s).

## Mounting a **FastAPI** application { #mounting-a-fastapi-application }

  /**
   * Returns the smallest power of two greater than or equal to {@code x}. This is equivalent to
   * {@code checkedPow(2, log2(x, CEILING))}.
   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @throws ArithmeticException of the next-higher power of two is not representable as a {@code
   *     long}, i.e. when {@code x > 2^62}
   * @since 20.0
   */

The new [Prefix.Compare] method compares two prefixes....

    // One invalid pair.
    assertEquals("abc", Strings.commonPrefix("abc\uD8AB\uDCABdef", "abc\uD8AB\uD8ABxyz"));
    // Two identical invalid pairs.
    assertEquals(
        "abc\uD8AB\uD8AC", Strings.commonPrefix("abc\uD8AB\uD8ACdef", "abc\uD8AB\uD8ACxyz"));
    // Two differing invalid pairs.
    assertEquals("abc\uD8AB", Strings.commonPrefix("abc\uD8AB\uD8ABdef", "abc\uD8AB\uD8ACxyz"));
    // One orphan high surrogate.

    void testCircuitClosesAfterSuccessThreshold() throws Exception {
        // Open the circuit
        circuitBreaker.tripBreaker();

        // Wait for timeout
        Thread.sleep(150);

        // Two successful calls should close the circuit
        circuitBreaker.call(() -> "success1");
        assertEquals(SimpleCircuitBreaker.State.HALF_OPEN, circuitBreaker.getState());

        circuitBreaker.call(() -> "success2");

So, **FastAPI** will take care of filtering out all the data that is not declared in the output model (using Pydantic).

### `response_model` or Return Type { #response-model-or-return-type }

In this case, because the two models are different, if we annotated the function return type as `UserOut`, the editor and tools would complain that we are returning an invalid type, as those are different classes.

// ReplicationLatency holds information of bucket operations latency, such us uploads
type ReplicationLatency struct {
	// Single & Multipart PUTs latency
	UploadHistogram LastMinuteHistogram
}

// Merge two replication latency into a new one
func (rl ReplicationLatency) merge(other ReplicationLatency) (newReplLatency ReplicationLatency) {
	newReplLatency.UploadHistogram = rl.UploadHistogram.Merge(other.UploadHistogram)
	return
}

When using **Pydantic v2**, the generated OpenAPI is a bit more exact and **correct** than before. 😎

In fact, in some cases, it will even have **two JSON Schemas** in OpenAPI for the same Pydantic model, for input and output, depending on if they have **default values**.

Let's see how that works and how to change it if you need to do that.

		// Range can only be numeric.
		{":9000", []string{"/export1{a...z}"}, false},
		// Duplicate disks not allowed.
		{":9000", []string{"/export1{1...32}", "/export1{1...32}"}, false},
		// Same host cannot export same disk on two ports - special case localhost.
		{":9001", []string{"http://localhost:900{1...2}/export{1...64}"}, false},
		// Valid inputs.
		{":9000", []string{"/export1"}, true},