feat(aws-cdk-lib): all L1s now have a isCfn<ResourceName> static helper to check if a value is this L1 resource

[mrgrain]

Issue # (if applicable)

N/A

Reason for this change

CloudFormation resource classes (CfnX) lack a type-safe way to check if an object is an instance of a specific resource type. This makes it difficult to perform runtime type checking with proper TypeScript type narrowing.

Description of changes

Adds a static isCfn<Resource> method to all generated CloudFormation resource classes. This method:

• Checks if the object is a CfnResource using the base class method
• Verifies the cfnResourceType matches the specific resource type
• Returns a TypeScript type predicate for proper type narrowing

Example generated method:

public static isCfnBucket(x: any): x is CfnBucket {
  return CfnResource.isCfnResource(x) && x.cfnResourceType === CfnBucket.CFN_RESOURCE_TYPE_NAME;
}

Implementation adds the makeIsAResource() method to the ResourceClass in spec2cdk, which generates this method for all CloudFormation resources.

Describe any new or updated permissions being added

None

Description of how you validated changes

Updated snapshot tests verify the method is generated correctly for all resource types.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

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• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • feat(aws-cdk-lib): all L1s now have a isCfn<ResourceName> static helper to check if a value is this L1 resource #36243
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  • feat(aws-cdk-lib): all L1s now have a isCfn<ResourceName> static helper to check if a value is this L1 resource #36243
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