Podría ser solo una o dos líneas de código, como:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Sadece bir-iki satır kod bile olabilir, örneğin:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Это могут быть буквально одна-две строки кода, например:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Cela pourrait être seulement une ou deux lignes de code, comme :

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Es könnten nur eine oder zwei Codezeilen sein, wie zum Beispiel:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Це можуть бути лише один-два рядки коду, наприклад:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

Poderia ser apenas uma ou duas linhas de código, como:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

In order to start a node with a trial license execute the following command:

-------------------------------------
./gradlew run -Drun.license_type=trial
-------------------------------------

This enables security and other paid features and adds a superuser with the username: `elastic-admin` and
password: `elastic-password`.

==== Other useful arguments

- In order to start a node with a different max heap space add: `-Dtests.heap.size=4G`

실제 콜백 코드는 여러분의 API 앱에 크게 의존합니다.

그리고 앱마다 많이 달라질 수 있습니다.

다음처럼 한두 줄의 코드일 수도 있습니다:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

하지만 콜백에서 가장 중요한 부분은, 여러분의 API 사용자(외부 개발자)가 콜백 요청 body로 *여러분의 API*가 보낼 데이터 등에 맞춰 *external API*를 올바르게 구현하도록 보장하는 것입니다.

    /**
     * Creates and returns a pair of two values.
     *
     * @param <T1>
     *            The type of the first value
     * @param <T2>
     *            The type of the second value
     * @param first
     *            The first value
     * @param second
     *            The second value
     * @return A pair of two values
     */
    public static <T1, T2> Pair<T1, T2> pair(final T1 first, final T2 second) {