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# Type of request: This is a ...

[x] bug report
[ ] feature request

# Detailed description
When I call the Lambda PutFunctionEventInvokeConfig API using the aws-java-sdk, the sdk throws an exception claiming it cannot parse the LastModified timestamp in the response:
```
software.amazon.awssdk.core.exception.SdkClientException: Unable to parse date : 2021-05-28T16:02:30.018Z
        at software.amazon.awssdk.core.exception.SdkClientException$BuilderImpl.build(SdkClientException.java:98)
        at software.amazon.awssdk.protocols.core.StringToInstant.lambda$safeParseDate$0(StringToInstant.java:77)
        at software.amazon.awssdk.protocols.core.StringToInstant.convert(StringToInstant.java:54)
        at software.amazon.awssdk.protocols.core.StringToInstant.convert(StringToInstant.java:32)
```

For comparison, the response for a getting a FunctionEventInvokeConfig for a Lambda of a real AWS account using the aws-cli is the following:
```
{
    "LastModified": "2021-05-27T19:26:43.454000-07:00",
    "FunctionArn": "...",
    ...
}
```

## Expected behavior
LambdaAsyncClient in aws-java-sdk should correctly parse the response for a PutFunctionEventInvokeConfig request.

## Actual behavior
LambdaAsyncClient in aws-java-sdk throws an exception when parsing the LastModified field in the response.

# Steps to reproduce

## Command used to start LocalStack
```
docker run -d --rm --name localstack -p 4566:4566 localstack/localstack:latest
```

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)
```
val putEventInvokeConfigRequest =
  PutFunctionEventInvokeConfigRequest.builder
    .functionName(functionName)
    .maximumEventAgeInSeconds(21600)
    .maximumRetryAttempts(0)
    .build
lambdaClient.putFunctionEventInvokeConfig(putEventInvokeConfigRequest)
```


arn = func_arn(function)
    qualifier = request.args.get('Qualifier')
    q_arn = func_qualifier(function, qualifier)
    result = add_permission_policy_statement(function, arn, q_arn)
    return result
def add_permission_policy_statement(resource_name, resource_arn, resource_arn_qualified):
    region = LambdaRegion.get()
    data = json.loads(to_str(request.data))
    iam_client = aws_stack.connect_to_service('iam')
    sid = data.get('StatementId')
    action = data.get('Action')
    principal = data.get('Principal')
    sourcearn = data.get('SourceArn')
    previous_policy = get_lambda_policy(resource_name)
    if resource_arn not in region.lambdas:
        return not_found_error(resource_arn)
    if not re.match(r'lambda:[*]|lambda:[a-zA-Z]+|[*]', action):
        return error_response('1 validation error detected: Value "%s" at "action" failed to satisfy '
                              'constraint: Member must satisfy regular expression pattern: '
                              '(lambda:[*]|lambda:[a-zA-Z]+|[*])' % action,
                              400, error_type='ValidationException')
    new_policy = generate_policy(sid, action, resource_arn_qualified, sourcearn, principal)