Addressing Heitor's feedback

Author: leandrodamascena

aws_lambda_powertools/event_handler/util.py

@@ -73,7 +73,7 @@ def extract_origin_header(resolver_headers: Dict[str, Any]):
 
 def _validate_openapi_security_parameters(
     security: List[Dict[str, List[str]]],
-    security_schemes: Optional[Dict[str, "SecurityScheme"]],
+    security_schemes: Optional[Dict[str, "SecurityScheme"]] = None,
 ) -> bool:
     """
     This function checks if all security requirements listed in the 'security'

docs/core/event_handler/api_gateway.md

@@ -1033,7 +1033,7 @@ Below is an example configuration for serving Swagger UI from a custom path or C
     No. Powertools adds support for generating OpenAPI documentation with [security schemes](https://swagger.io/docs/specification/authentication/), but it doesn't implement any of the security schemes itself, so you must implement the security mechanisms separately.
 
 OpenAPI uses the term security scheme for [authentication and authorization schemes](https://swagger.io/docs/specification/authentication/){target="_blank"}.
-When you're describing your API, declare security schemes at the top level, and reference them globally or per operation.
+When you're describing your API, declare security schemes at the top level, and reference them globally or per operation. Remember to have the security configurations defined in the `security_schemes`, otherwise a `SchemaValidationError` will be raised.
 
 === "Global OpenAPI security schemes"