v, _, _, err := env.LookupEnv(config.EnvArgs)
	if err != nil {
		logger.FatalIf(err, "Unable to validate passed arguments in %s:%s",
			config.EnvArgs, os.Getenv(config.EnvArgs))
	}
	if v == "" {
		v, _, _, err = env.LookupEnv(config.EnvVolumes)
		if err != nil {
			logger.FatalIf(err, "Unable to validate passed arguments in %s:%s",
				config.EnvVolumes, os.Getenv(config.EnvVolumes))
		}
	}
	if v == "" {

        }

        @Override
        public SSPContext createContext(CIFSContext tc, String targetDomain, String host, byte[] initialToken, boolean doSigning)
                throws SmbException {
            // Validate required argument and interact with the provided CIFSContext
            if (tc == null) {
                throw new NullPointerException("tc");
            }

        assertEquals("childuser", testConfig.getDefaultUsername()); // Overridden
        assertEquals("parentdomain", testConfig.getDefaultDomain()); // Inherited
    }

    @Test
    @DisplayName("Should validate configuration consistency")
    void testConfigurationValidation() throws CIFSException {
        // Given
        Properties props = new Properties();
        props.setProperty("jcifs.smb.client.minVersion", "SMB311");

			if errCode != testCase.expected {
				t.Errorf("(%d) expected to get success, instead got %s", i, niceError(errCode))
			}
		}
	}
}

// TestValidateV2AuthHeader - Tests validate the logic of V2 Authorization header validator.
func TestValidateV2AuthHeader(t *testing.T) {
	ctx, cancel := context.WithCancel(t.Context())
	defer cancel()

	obj, fsDir, err := prepareFS(ctx)
	if err != nil {

	cleanQ := cleanEntitiesQuery{
		Users:    make(map[string]set.StringSet),
		Groups:   set.CreateStringSet(q.Groups...),
		Policies: set.CreateStringSet(q.Policy...),
	}

	if ldap {
		// Validate and normalize users, then fetch and normalize their groups
		// Also include unvalidated users for backward compatibility.
		for _, user := range q.Users {

	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
	region := globalSite.Region()
	config.SetRegion(region)
	if err = config.Validate(region, globalEventNotifier.targetList); err != nil {
		arnErr, ok := err.(*event.ErrARNNotFound)
		if ok {
			for i, queue := range config.QueueList {
				// Remove ARN not found queues, because we previously allowed

        // Act & Assert: attempting to call any method on null should throw NPE
        Assertions.assertThrows(NullPointerException.class, () -> {
            // Intentionally dereference null to validate exception behavior
            // This checks that callers must handle null references defensively
            info.getSize();
        });
    }

```

</div>

Then go to the `/docs` UI, you will see that **FastAPI** is using these **models** to **document** the API, and it will use them to **serialize** and **validate** the data too.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Update the App with Multiple Models { #update-the-app-with-multiple-models }

        Address address = nameServiceClient.getByName("localhost", false);

        // Then
        assertNotNull(address, "Should return address for localhost");
    }

    @Test
    @DisplayName("Should validate context configuration access")
    void testContextAccess() {
        // When
        NameServiceClientImpl client = new NameServiceClientImpl(mockContext);

        // Then

	// Adds 'crossdomain.xml' policy middleware to serve legacy flash clients.
	setCrossDomainPolicyMiddleware,
	// Limits all body and header sizes to a maximum fixed limit
	setRequestLimitMiddleware,
	// Validate all the incoming requests.
	setRequestValidityMiddleware,
	// Add upload forwarding middleware for site replication
	setUploadForwardingMiddleware,
	// Add bucket forwarding middleware
	setBucketForwardingMiddleware,