class Message(BaseModel):
    input: str
    output: MessageOutput


app = FastAPI(title="Minimal FastAPI App", version="1.0.0")


@app.post("/messages", response_model=Message)
async def create_message(input_message: str) -> Message:
    return Message(
        input=input_message,
        output=MessageOutput(body=f"Processed: {input_message}"),
    )


client = TestClient(app)

        return OptionalThing.of(asJson(createFailureBean(Status.BAD_REQUEST, createMessage(resource, cause))));
    }

    @Override
    public OptionalThing<ApiResponse> handleServerException(final ApiFailureResource resource, final Throwable cause) {
        return OptionalThing.of(asJson(createFailureBean(Status.SYSTEM_ERROR, createMessage(resource, cause))));
    }

     */
    public SAXRuntimeException(final SAXException cause) {
        super("ECL0054", asArray(createMessage(cause)), cause);
    }

    /**
     * Creates a message.
     *
     * @param cause the underlying exception
     * @return the message
     */
    protected static String createMessage(final SAXException cause) {
        final StringBuilder buf = new StringBuilder(100);
        buf.append(cause);

    }

    /**
     * Creates a new messages instance for handling validation and user messages.
     * This method can be called by the application to create message containers.
     *
     * @return a new FessMessages instance
     */
    @Override
    public FessMessages createMessages() { // application may call