Secret Manager generateSecretString and generateStringKey must be specified together

Secret manager Secret creation in the cdk require to mention both generateSecretString and generateStringKey together. This is not required in cloudformation.

I can help implementing if needed I just posted it not to forget.

Reproduction Steps

       import * as cdkSecret from '@aws-cdk/aws-secretsmanager';

        new cdkSecret.Secret(
          this, 'Secret' + instance, {
          generateSecretString: {
            secretStringTemplate: JSON.stringify({ 
              username: "hello-secret",
            }),
            // generateStringKey should't be required 
            generateStringKey: 'tmp'
          }
        });

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This is 🐛 Bug Report

[pushthat]

You could for example aggregate multiple secrets from other secrets into one big. I see what you sent in the documentation @jogold however this template is valid and deploy in cloudformation :

  Secret: 
    Type: AWS::SecretsManager::Secret 
    Properties: 
      Description: "my description" 
      Name:  "test"
      GenerateSecretString: 
        SecretStringTemplate: !Sub '{"username": "test"}' 

There’s an inconsistency between cdk and cloudformation.

[pushthat]

Seams that now it is consistent