fix(core): properties set to false are not rendered in the template (#…

…10539)

Any CloudFormation resource that defines a single boolean property set
to false is not rendered to the CloudFormation template.

The bug is in implementation of `_toCloudFormation()` API in
`CfnResource`. It treated `false` and `undefined` the same way.

fixes #10455


----

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

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

@@ -306,7 +306,10 @@ export class CfnResource extends CfnRefElement {
             Condition: this.cfnOptions.condition && this.cfnOptions.condition.logicalId,
           }, props => {
             const renderedProps = this.renderProperties(props.Properties || {});
-            props.Properties = renderedProps && (Object.values(renderedProps).find(v => !!v) ? renderedProps : undefined);
+            if (renderedProps) {
+              const hasDefined = Object.values(renderedProps).find(v => v !== undefined);
+              props.Properties = hasDefined !== undefined ? renderedProps : undefined;
+            }
             return deepMerge(props, this.rawOverrides);
           }),
         },

packages/@aws-cdk/core/test/test.cfn-resource.ts

@@ -25,6 +25,30 @@ export = nodeunit.testCase({
 
       test.done();
     },
+
+    'renders "Properties" for a resource that has only properties set to "false"'(test: nodeunit.Test) {
+      const app = new core.App();
+      const stack = new core.Stack(app, 'TestStack');
+      new core.CfnResource(stack, 'Resource', {
+        type: 'Test::Resource::Fake',
+        properties: {
+          FakeProperty: false,
+        },
+      });
+
+      test.deepEqual(app.synth().getStackByName(stack.stackName).template, {
+        Resources: {
+          Resource: {
+            Type: 'Test::Resource::Fake',
+            Properties: {
+              FakeProperty: false,
+            },
+          },
+        },
+      });
+
+      test.done();
+    },
   },
 
   'applyRemovalPolicy default includes Update policy'(test: nodeunit.Test) {