OpenAPI: Fix arrays without items

As explained in the documentation `arrays` have an `items` section, and
arrays that can have arbitrary values are defined like this [1]:

```
type: array
items: {}
```

In the cinder schemas we have a couple of cases where we are defining an
`array` without `items`, all other arrays in the openapi codebase seem
to be right.

In this patch we fix these issues and introduce code in the
`_sanitize_schema` to detect future cases of this issue and fix the
schema automatically for the output.

[1]: https://swagger.io/docs/specification/v3_0/data-models/data-types/#mixed-type-arrays

Change-Id: I49cadcccf64ed9699a4b41674109b4afbfa1e106

codegenerator/openapi/base.py

@@ -1208,18 +1208,18 @@ class OpenStackServerSourceBase:
                 typ = v.get("type")
                 if typ == "object":
                     schema.properties[k] = self._sanitize_schema(v)
-                if typ == "array" and "additionalItems" in v:
-                    # additionalItems have nothing to do under the type array (create servergroup)
-                    schema.properties[k].pop("additionalItems")
-                if (
-                    typ == "array"
-                    and "items" in v
-                    and isinstance(v["items"], list)
-                ):
-                    # server_group create - type array "items" is a dict and not list
-                    # NOTE: server_groups recently changed to "prefixItems",
-                    # so this may be not necessary anymore
-                    schema.properties[k]["items"] = v["items"][0]
+                if typ == "array":
+                    if "additionalItems" in v:
+                        # additionalItems have nothing to do under the type array (create servergroup)
+                        schema.properties[k].pop("additionalItems")
+                    # Arrays must always have 'items'
+                    if "items" not in v:
+                        schema.properties[k]["items"] = {}
+                    elif isinstance(v["items"], list):
+                        # server_group create - type array "items" is a dict and not list
+                        # NOTE: server_groups recently changed to "prefixItems",
+                        # so this may be not necessary anymore
+                        schema.properties[k]["items"] = v["items"][0]
         if start_version and self._api_ver_major(start_version) not in [
             "0",
             0,

codegenerator/openapi/cinder_schemas/extension.py

@@ -27,7 +27,7 @@ EXTENSION_SCHEMA: dict[str, Any] = {
             "type": "string",
             "description": "The extension description.",
         },
-        "links": {"type": "array", "description": ""},
+        "links": {"type": "array", "description": "", "items": {}},
         "alias": {
             "type": "string",
             "description": "The alias for the extension. For example, “FOXNSOX”, “os- availability-zone”, “os-extended-quotas”, “os- share-unmanage” or “os-used-limits.”",

codegenerator/openapi/cinder_schemas/limit.py

@@ -21,7 +21,7 @@ LIMITS_SCHEMA: dict[str, Any] = {
         "limits": {
             "type": "object",
             "properties": {
-                "rate": {"type": "array"},
+                "rate": {"type": "array", "items": {}},
                 "absolute": {
                     "type": "object",
                     "properties": {