fix(apigateway): json schema additionalProperties should be boolean (#3997)

* Add support for json schema additionalProperties

* Change it to boolean according to code review

* add breaking change exclusions

Author: daiwei920

allowed-breaking-changes.txt

@@ -16,3 +16,6 @@ incompatible-argument:@aws-cdk/aws-lambda.Function.<initializer>
 incompatible-argument:@aws-cdk/aws-lambda.SingletonFunction.<initializer>
 incompatible-argument:@aws-cdk/aws-lambda.Function.addEnvironment
 changed-type:@aws-cdk/aws-dynamodb.Table.tableStreamArn
+incompatible-argument:@aws-cdk/aws-apigateway.LambdaRestApi.addModel
+incompatible-argument:@aws-cdk/aws-apigateway.Model.<initializer>
+incompatible-argument:@aws-cdk/aws-apigateway.RestApi.addModel

packages/@aws-cdk/aws-apigateway/lib/json-schema.ts

@@ -63,7 +63,7 @@ export interface JsonSchema {
   readonly minProperties?: number;
   readonly required?: string[];
   readonly properties?: { [name: string]: JsonSchema };
-  readonly additionalProperties?: JsonSchema;
+  readonly additionalProperties?: boolean;
   readonly patternProperties?: { [name: string]: JsonSchema };
   readonly dependencies?: { [name: string]: JsonSchema | string[] };
   readonly propertyNames?: JsonSchema;