String msg = ModelBuildingException.toMessage("modelId", Arrays.asList(pb1, pb2));
        assertEquals(
                "2 problems were encountered while building the effective model for modelId" + System.lineSeparator()
                        + "    - [ERROR] message1" + System.lineSeparator()
                        + "    - [ERROR] message2",
                msg);

```Python hl_lines="9-14  17"
{!../../docs_src/custom_response/tutorial009c.py!}
```

Statt:

```json
{"message": "Hello World"}
```

... wird die Response jetzt Folgendes zurückgeben:

```json
{
  "message": "Hello World"
}
```

Natürlich werden Sie wahrscheinlich viel bessere Möglichkeiten finden, Vorteil daraus zu ziehen, als JSON zu formatieren. 😉

    // it.
    executeListener(runnable, executor);
  }

  /**
   * Runs this execution list, executing all existing pairs in the order they were added. However,
   * note that listeners added after this point may be executed before those previously added, and
   * note that the execution order of all listeners is ultimately chosen by the implementations of

     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */
    Model assembleModelInheritance(
            Model child, Model parent, ModelBuildingRequest request, ModelProblemCollector problems);

     */
    String getDomain ();


    /**
     * @return the share this referral points to
     */
    String getShare ();


    /**
     * @return the number of characters from the unc path that were consumed by this referral
     */
    int getPathConsumed ();


    /**
     * @return the replacement path for this referal
     */
    String getPath ();


    /**

    }

    public String toString() {
        return render("");
    }

    public String render(String indentation) {
        if (messages.size() == 0) {
            return indentation + "There were no validation errors.";
        }

        StringBuilder message = new StringBuilder();

        //        if ( messages.size() == 1 )
        //        {

* Erstellen Sie eine Datei `main.py` mit:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

* Crea un file `main.py` con:

```Python
from fastapi import FastAPI
from typing import Optional

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = Optional[None]):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

     *            be <code>null</code>.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */
    void injectManagement(Model model, ModelBuildingRequest request, ModelProblemCollector problems);

     *            <code>null</code>.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */
    void injectManagement(Model model, ModelBuildingRequest request, ModelProblemCollector problems);