* This map is usually either empty if no module was found, or a singleton map.
     * It may however contain more than one entry if module hierarchy was detected,
     * in which case there is one key per sub-directory.
     *
     * <p>This map may contain null values if the constructor was invoked with {@code resolve}
     * parameter set to false. This is more efficient when only the module existence needs to

    @Override
    public List<String> getModelIds() {
        return modelIds;
    }

    public DefaultModelBuilderResult addModelId(String modelId) {
        // Intentionally notNull because Super POM may not contain a modelId
        Objects.requireNonNull(modelId, "modelId cannot be null");

        modelIds.add(modelId);

        return this;
    }

    @Override
    public Model getRawModel() {

  // stomped by the controller.
  // +optional
  optional AggregationRule aggregationRule = 3;
}

// ClusterRoleBinding references a ClusterRole, but not contain it.  It can reference a ClusterRole in the global namespace,
// and adds who information via Subject.
message ClusterRoleBinding {
  // Standard object's metadata.
  // +optional

    mmHeap.addAll(Lists.newArrayList(1, 1, 2));
    assertEquals(3, mmHeap.size());
    assertFalse("Heap does not contain null", mmHeap.contains(null));
    assertFalse("Heap does not contain 3", mmHeap.contains(3));
    assertFalse("Heap does not contain 3", mmHeap.remove(3));
    assertEquals(3, mmHeap.size());
    assertTrue("Heap is not intact after remove()", mmHeap.isIntact());

Let's say you have a *path operation* with a path `/files/{file_path}`.

But you need `file_path` itself to contain a *path*, like `home/johndoe/myfile.txt`.

So, the URL for that file would be something like: `/files/home/johndoe/myfile.txt`.

### OpenAPI support

OpenAPI doesn't support a way to declare a *path parameter* to contain a *path* inside, as that could lead to scenarios that are difficult to test and define.

   * whose elements are the result of applying {@code elementFunction} to the inputs, with counts
   * equal to the result of applying {@code countFunction} to the inputs.
   *
   * <p>If the mapped elements contain duplicates (according to {@code comparator}), the first
   * occurrence in encounter order appears in the resulting multiset, with count equal to the sum of

   * whose elements are the result of applying {@code elementFunction} to the inputs, with counts
   * equal to the result of applying {@code countFunction} to the inputs.
   *
   * <p>If the mapped elements contain duplicates (according to {@code comparator}), the first
   * occurrence in encounter order appears in the resulting multiset, with count equal to the sum of

  // stomped by the controller.
  // +optional
  optional AggregationRule aggregationRule = 3;
}

// ClusterRoleBinding references a ClusterRole, but not contain it.  It can reference a ClusterRole in the global namespace,
// and adds who information via Subject.
// Deprecated in v1.17 in favor of rbac.authorization.k8s.io/v1 ClusterRoleBinding, and will no longer be served in v1.22.

  // stomped by the controller.
  // +optional
  optional AggregationRule aggregationRule = 3;
}

// ClusterRoleBinding references a ClusterRole, but not contain it.  It can reference a ClusterRole in the global namespace,
// and adds who information via Subject.
// Deprecated in v1.17 in favor of rbac.authorization.k8s.io/v1 ClusterRoleBinding, and will no longer be served in v1.22.

## The normal **FastAPI** app

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

This part is pretty normal, most of the code is probably already familiar to you:

```Python hl_lines="9-13  36-53"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

!!! tip