docs: include IdempotencyValidationError in example

Author: heitorlessa

docs/utilities/idempotency.md

@@ -800,8 +800,6 @@ This utility will raise an **`IdempotencyAlreadyInProgressError`** exception if
 
 This is a locking mechanism for correctness. Since we don't know the result from the first invocation yet, we can't safely allow another concurrent execution.
 
-When enabled, the default is to cache a maximum of 256 records in each Lambda execution environment - You can change it with the **`local_cache_max_items`** parameter.
-
 ### Payload validation
 
 ???+ question "Question: What if your function is invoked with the same payload except some outer parameters have changed?"
@@ -813,7 +811,7 @@ With **`payload_validation_jmespath`**, you can provide an additional JMESPath e
 
 === "Payload validation"
 
-    ```python hl_lines="16 25 32"
+    ```python hl_lines="20 29 36"
     --8<-- "examples/idempotency/src/working_with_validation_payload.py"
     ```
 

examples/idempotency/src/working_with_validation_payload.py

@@ -2,13 +2,17 @@
 from dataclasses import dataclass, field
 from uuid import uuid4
 
+from aws_lambda_powertools import Logger
 from aws_lambda_powertools.utilities.idempotency import (
     DynamoDBPersistenceLayer,
     IdempotencyConfig,
     idempotent,
 )
+from aws_lambda_powertools.utilities.idempotency.exceptions import IdempotencyValidationError
 from aws_lambda_powertools.utilities.typing import LambdaContext
 
+logger = Logger()
+
 table = os.getenv("IDEMPOTENCY_TABLE")
 persistence_layer = DynamoDBPersistenceLayer(table_name=table)
 config = IdempotencyConfig(
@@ -38,6 +42,12 @@ def lambda_handler(event: dict, context: LambdaContext):
             "message": "success",
             "statusCode": 200,
         }
+    except IdempotencyValidationError:
+        logger.exception("Payload tampering detected", payment=payment, failure_type="validation")
+        return {
+            "message": "Unable to process payment at this time. Try again later.",
+            "statusCode": 500,
+        }
     except Exception as exc:
         raise PaymentError(f"Error creating payment {str(exc)}")