fix(cfn-include): allow boolean values for string-typed properties (#13508)

CloudFormation is pretty lax when it comes to the types it accepts,
and allows passing a boolean where a string is expected.
Allow that possibility in cloudformation-include.

----

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

Author: skinny85

packages/@aws-cdk/cloudformation-include/test/test-templates/boolean-for-string.json

@@ -0,0 +1,10 @@
+{
+  "Resources": {
+    "Bucket": {
+      "Type": "AWS::S3::Bucket",
+      "Properties": {
+        "AccessControl": true
+      }
+    }
+  }
+}

packages/@aws-cdk/cloudformation-include/test/valid-templates.test.ts

@@ -116,6 +116,14 @@ describe('CDK Include', () => {
     );
   });
 
+  test('accepts booleans for properties with type string', () => {
+    includeTestTemplate(stack, 'boolean-for-string.json');
+
+    expect(stack).toMatchTemplate(
+      loadTestFileToJsObject('boolean-for-string.json'),
+    );
+  });
+
   test('correctly changes the logical IDs, including references, if imported with preserveLogicalIds=false', () => {
     const cfnTemplate = includeTestTemplate(stack, 'bucket-with-encryption-key.json', {
       preserveLogicalIds: false,

packages/@aws-cdk/core/lib/cfn-parse.ts

@@ -132,6 +132,12 @@ export class FromCloudFormation {
       return new FromCloudFormationResult(value.toString());
     }
 
+    // CloudFormation treats booleans and strings interchangeably;
+    // so, if we get a boolean here, convert it to a string
+    if (typeof value === 'boolean') {
+      return new FromCloudFormationResult(value.toString());
+    }
+
     // in all other cases, just return the input,
     // and let a validator handle it if it's not a string
     return new FromCloudFormationResult(value);