fix(lambda-event-sources): event source property maxConcurrency is no…

…t token-aware (#27797)

Allows a Token to be provided for maxConcurrency without runtime errors

Closes #27796.

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

packages/aws-cdk-lib/aws-lambda/lib/event-source-mapping.ts

@@ -345,7 +345,7 @@ export class EventSourceMapping extends cdk.Resource implements IEventSourceMapp
       throw new Error(`maxBatchingWindow cannot be over 300 seconds, got ${props.maxBatchingWindow.toSeconds()}`);
     }
 
-    if (props.maxConcurrency && (props.maxConcurrency < 2 || props.maxConcurrency > 1000)) {
+    if (props.maxConcurrency && !cdk.Token.isUnresolved(props.maxConcurrency) && (props.maxConcurrency < 2 || props.maxConcurrency > 1000)) {
       throw new Error('maxConcurrency must be between 2 and 1000 concurrent instances');
     }
 

packages/aws-cdk-lib/aws-lambda/test/event-source-mapping.test.ts

@@ -60,6 +60,14 @@ describe('event source mapping', () => {
     })).toThrow(/maxConcurrency must be between 2 and 1000 concurrent instances/);
   });
 
+  test('does not throw if maxConcurrency is a token', () => {
+    expect(() => new EventSourceMapping(stack, 'test', {
+      target: fn,
+      eventSourceArn: '',
+      maxConcurrency: cdk.Token.asNumber({ Ref: 'abc' }),
+    })).not.toThrow();
+  });
+
   test('maxConcurrency appears in stack', () => {
     new EventSourceMapping(stack, 'test', {
       target: fn,