api("com.uwyn:jhighlight:1.0")
        api("com.vladsch.flexmark:flexmark-all:0.34.60") {
            because("Higher versions tested are either incompatible (0.62.2) or bring additional unwanted dependencies (0.36.8)")
        }
        api("org.apache.pdfbox:pdfbox:2.0.24") {
            because("Flexmark 0.34.60 brings in a vulnerable version of pdfbox")
        }
        api("com.google.code.findbugs:jsr305:3.0.2")

<img src="/img/tutorial/sub-applications/image02.png">

If you try interacting with any of the two user interfaces, they will work correctly, because the browser will be able to talk to each specific app or sub-app.

### Technical Details: `root_path` { #technical-details-root-path }

{* ../../docs_src/response_model/tutorial003_02_py39.py hl[8,10:11] *}

This simple case is handled automatically by FastAPI because the return type annotation is the class (or a subclass of) `Response`.

And tools will also be happy because both `RedirectResponse` and `JSONResponse` are subclasses of `Response`, so the type annotation is correct.

### Annotate a Response Subclass { #annotate-a-response-subclass }

Because all the **fields actually change** (the type now includes `None` and they now have a default value of `None`), we need to **re-declare** them.

import org.gradle.process.ExecOperations
import org.gradle.process.ExecResult
import java.io.File
import javax.inject.Inject
import org.gradle.work.DisableCachingByDefault

@DisableCachingByDefault(because = "Must not cache because it modifies global Android home")
abstract class AndroidHomeWarmupTask : DefaultTask() {

    @get:OutputDirectory
    abstract val warmupProjectsDirectory: DirectoryProperty

    @get:Input

ItemsService.createItemItemsPost({name: "Plumbus", price: 5})
```

...that's because the client generator uses the OpenAPI internal **operation ID** for each *path operation*.

OpenAPI requires that each operation ID is unique across all the *path operations*, so FastAPI uses the **function name**, the **path**, and the **HTTP method/operation** to generate that operation ID, because that way it can make sure that the operation IDs are unique.

The way to describe this in OpenAPI, is to mark that field as **required**, because it will always be there.

Because of that, the JSON Schema for a model can be different depending on if it's used for **input or output**:

* for **input** the `description` will **not be required**

Let's imagine that loading the model can **take quite some time**, because it has to read a lot of **data from disk**. So you don't want to do it for every request.

## Standards-based benefits, alternative documentation { #standards-based-benefits-alternative-documentation }

And because the generated schema is from the <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md" class="external-link" target="_blank">OpenAPI</a> standard, there are many compatible tools.

# Extra Models { #extra-models }

Continuing with the previous example, it will be common to have more than one related model.

This is especially the case for user models, because:

* The **input model** needs to be able to have a password.
* The **output model** should not have a password.
* The **database model** would probably need to have a hashed password.

/// danger