Addressed review comments

Author: Tarun Belani

packages/@aws-cdk/aws-imagebuilder-alpha/lib/distribution-configuration.ts

@@ -543,6 +543,11 @@ export class DistributionConfiguration extends DistributionConfigurationBase {
         );
       }
 
+      const { region: _, ...amiDistributionWithoutRegion }: AmiDistribution = amiDistribution;
+      if (Object.keys(amiDistributionWithoutRegion).length === 0) {
+        throw new cdk.ValidationError('at least one AMI distribution property must be set', this);
+      }
+
       this.amiDistributionsByRegion[region] = amiDistribution;
     });
   }

packages/@aws-cdk/aws-imagebuilder-alpha/test/distribution-configuration.test.ts

@@ -528,6 +528,14 @@ describe('Distribution Configuration', () => {
     }).toThrow(cdk.ValidationError);
   });
 
+  test('throws a validation error when no properties are defined on an AMI distribution', () => {
+    const distributionConfiguration = new DistributionConfiguration(stack, 'DistributionConfiguration');
+
+    expect(() => {
+      distributionConfiguration.addAmiDistributions({ region: 'us-east-1' });
+    }).toThrow(cdk.ValidationError);
+  });
+
   test('throws a validation error when providing a max parallel launch below 6 for fast launch configurations', () => {
     const distributionConfiguration = new DistributionConfiguration(stack, 'DistributionConfiguration');
     distributionConfiguration.addAmiDistributions({ fastLaunchConfigurations: [{ maxParallelLaunches: 5 }] });