fix(s3-deployment): Source.jsonData() fails with null JSON values

packages/@aws-cdk-testing/framework-integ/test/aws-s3-deployment/test/integ.bucket-deployment-data.ts

@@ -64,6 +64,9 @@ class TestBucketDeploymentData extends Stack {
     // Test empty string handling
     const file8 = Source.data('file8.txt', '');
 
+    // Test null JSON data value
+    const file9 = Source.jsonData('my-json/config-with-null.json', { hello: "there", goodbye: null })
+
     const deployment = new BucketDeployment(this, 'DeployWithDataSources', {
       destinationBucket: this.bucket,
       sources: [file1, file2],
@@ -77,6 +80,7 @@ class TestBucketDeploymentData extends Stack {
     deployment.addSource(file6);
     deployment.addSource(file7);
     deployment.addSource(file8);
+    deployment.addSource(file9);
 
     new CfnOutput(this, 'BucketName', { value: this.bucket.bucketName });
   }
@@ -105,6 +109,17 @@ assertionProvider.expect(ExpectedResult.objectLike({
   Body: '{"secret_value":"test\\"with\\"quotes"}',
 }));
 
+// Assert that JSON data with a null value is represented properly
+const jsonNullAssertionProvider = integTest.assertions.awsApiCall('S3', 'getObject', {
+  Bucket: testCase.bucket.bucketName,
+  Key: path.join('deploy/here', 'my-json/config-with-null.json'),
+});
+
+// Verify the content is valid JSON and both null and non-null fields are present
+jsonNullAssertionProvider.expect(ExpectedResult.objectLike({
+  Body: '{"hello":"there","goodbye":null}',
+}));
+
 // Add assertions to verify the YAML file
 const yamlAssertionProvider = integTest.assertions.awsApiCall('S3', 'getObject', {
   Bucket: testCase.bucket.bucketName,

packages/aws-cdk-lib/aws-s3-deployment/lib/source.ts

@@ -275,7 +275,7 @@ export class Source {
       return obj.map(v => Source.escapeTokens(scope, v));
     }
 
-    if (typeof obj === 'object') {
+    if (obj !== null && typeof obj === 'object') {
       return Object.fromEntries(
         Object.entries(obj).map(([key, value]) => {
           // As JSON keys are always strings, keys are assumed to be either regular strings or string tokens.

packages/aws-cdk-lib/aws-s3-deployment/test/bucket-deployment.test.ts

@@ -1429,6 +1429,7 @@ test('Source.jsonData() can be used to create a file with a JSON object', () =>
 
   const config = {
     foo: 'bar',
+    baz: null,
     sub: {
       hello: bucket.bucketArn,
     },
@@ -1441,7 +1442,7 @@ test('Source.jsonData() can be used to create a file with a JSON object', () =>
   });
 
   const result = app.synth();
-  expect(readDataFile(result, 'app-config.json')).toBe('{"foo":"bar","sub":{"hello":<<marker:0xbaba:0>>},"<<marker:0xbaba:1>>":"Token can be a key as well!"}');
+  expect(readDataFile(result, 'app-config.json')).toBe('{"foo":"bar","baz":null,"sub":{"hello":<<marker:0xbaba:0>>},"<<marker:0xbaba:1>>":"Token can be a key as well!"}');
 
   // verify marker is mapped to the bucket ARN in the resource props
   Template.fromJSON(result.stacks[0].template).hasResourceProperties('Custom::CDKBucketDeployment', {