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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)
```


source = source_arn.split(':')[2].lower()
    source = 'kafka' if 'secretsmanager' in source else source
    batch_size_entry = BATCH_SIZE_RANGES.get(source)
    if not batch_size_entry:
        raise ValueError(
            INVALID_PARAMETER_VALUE_EXCEPTION, 'Unsupported event source type'
        )
    batch_size = batch_size or batch_size_entry[0]
    if batch_size > batch_size_entry[1]:
        raise ValueError(
            INVALID_PARAMETER_VALUE_EXCEPTION,
            'BatchSize {} exceeds the max of {}'.format(batch_size, batch_size_entry[1])
        )
    return batch_size
def add_function_mapping(lambda_name, lambda_handler, lambda_cwd=None):
    region = LambdaRegion.get()
    arn = func_arn(lambda_name)
    lambda_details = region.lambdas[arn]
    lambda_details.versions.get(VERSION_LATEST)['Function'] = lambda_handler
    lambda_details.cwd = lambda_cwd or lambda_details.cwd
def build_mapping_obj(data):