chore: force ellipsis in API webmethods (#2141)

# What does this PR do?

This new check will fail if some webmethods are missing the ellipsis:

```
API Method Return Type Validation Errors:

Method Api.eval.job_result does not contain ellipsis (...) in its implementation
Method Api.agents.create_agent_turn does not contain ellipsis (...) in its implementation
Method Api.agents.create_openai_response does not contain ellipsis (...) in its implementation
Method Api.eval.evaluate_rows does not contain ellipsis (...) in its implementation
Method Api.eval.run_eval does not contain ellipsis (...) in its implementation
```

Unless not implemented.

Signed-off-by: Sébastien Han <seb@redhat.com>

docs/openapi_generator/generate.py

@@ -44,7 +44,7 @@ def main(output_dir: str):
     if return_type_errors:
         print("\nAPI Method Return Type Validation Errors:\n")
         for error in return_type_errors:
-            print(error)
+            print(error, file=sys.stderr)
         sys.exit(1)
     now = str(datetime.now())
     print(

docs/openapi_generator/pyopenapi/utility.py

@@ -174,14 +174,25 @@ def _validate_list_parameters_contain_data(method) -> str | None:
         return "does not have a mandatory data attribute containing the list of objects"
 
 
+def _validate_has_ellipsis(method) -> str | None:
+    source = inspect.getsource(method)
+    if "..." not in source and not "NotImplementedError" in source:
+        return "does not contain ellipsis (...) in its implementation"
+
+
 _VALIDATORS = {
     "GET": [
         _validate_api_method_return_type,
         _validate_list_parameters_contain_data,
         _validate_api_method_doesnt_return_list,
+        _validate_has_ellipsis,
     ],
     "DELETE": [
         _validate_api_delete_method_returns_none,
+        _validate_has_ellipsis,
+    ],
+    "POST": [
+        _validate_has_ellipsis,
     ],
 }