logRetention field is deprecated, logGroup is required

[nsteffens]

Environment information

❯ npx ampx info                                                                                                                                                                                           
System:
  OS: macOS 15.6
  CPU: (12) arm64 Apple M3 Pro
  Memory: 193.63 MB / 36.00 GB
  Shell: /bin/zsh
Binaries:
  Node: 22.14.0 - ~/.nvm/versions/node/v22.14.0/bin/node
  Yarn: undefined - undefined
  npm: 10.9.2 - ~/.nvm/versions/node/v22.14.0/bin/npm
  pnpm: undefined - undefined
NPM Packages:
  @aws-amplify/auth-construct: 1.8.1
  @aws-amplify/backend: 1.16.1
  @aws-amplify/backend-ai: Not Found
  @aws-amplify/backend-auth: 1.7.1
  @aws-amplify/backend-cli: 1.8.0
  @aws-amplify/backend-data: 1.6.1
  @aws-amplify/backend-deployer: 2.1.3
  @aws-amplify/backend-function: 1.14.1
  @aws-amplify/backend-output-schemas: 1.7.0
  @aws-amplify/backend-output-storage: 1.3.1
  @aws-amplify/backend-secret: 1.4.0
  @aws-amplify/backend-storage: 1.4.1
  @aws-amplify/cli-core: 2.2.1
  @aws-amplify/client-config: 1.8.0
  @aws-amplify/data-construct: 1.16.3
  @aws-amplify/data-schema: 1.21.1
  @aws-amplify/deployed-backend-client: 1.8.0
  @aws-amplify/form-generator: 1.2.4
  @aws-amplify/model-generator: 1.2.0
  @aws-amplify/platform-core: 1.10.0
  @aws-amplify/plugin-types: 1.11.0
  @aws-amplify/sandbox: 2.1.2
  @aws-amplify/schema-generator: 1.4.0
  @aws-cdk/toolkit-lib: 1.1.1
  aws-amplify: 6.15.5
  aws-cdk-lib: 2.211.0
  typescript: 5.9.2
AWS environment variables:
  AWS_PROFILE = XXXXXXXXXXXXXXXXX

Describe the bug

I have a very simple lambda function added:

import { defineFunction } from "@aws-amplify/backend";

export const taskDispatcher = defineFunction({
  name: "task-dispatcher",
  entry: "./handler.ts",
  timeoutSeconds: 10,
  logging: {
    retention: "1 month",
  },
});

This compiles fine, still shows this warning for all of my lambdas:

3:58:11 PM [WARNING] aws-cdk-lib.aws_lambda.FunctionOptions#logRetention is deprecated.
3:58:11 PM   use `logGroup` instead
3:58:11 PM   This API will be removed in the next major release.

Furthermore, the whole logging field is not documented. I only found out about this by accident in a PR in this repo..

Reproduction steps

Use the example above. Run it. Warning appears.