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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)
```


def __init__(self, msg, code=400):
        super(ClientError, self).__init__(msg)
        self.code = code
        self.msg = msg
    def get_response(self):
        if isinstance(self.msg, Response):
            return self.msg
        return error_response(self.msg, self.code)
class LambdaContext(object):
    DEFAULT_MEMORY_LIMIT = 1536
    def __init__(self, func_details, qualifier=None, context=None):
        self.function_name = func_details.name()
        self.function_version = func_details.get_qualifier_version(qualifier)
        self.client_context = context.get('client_context')
        self.invoked_function_arn = func_details.arn()
        if qualifier:
            self.invoked_function_arn += ':' + qualifier
        self.cognito_identity = context.get('identity')
        self.aws_request_id = str(uuid.uuid4())
        self.memory_limit_in_mb = func_details.memory_size or self.DEFAULT_MEMORY_LIMIT
        self.log_group_name = '/aws/lambda/%s' % self.function_name
        self.log_stream_name = '%s/[1]%s' % (timestamp(format='%Y/%m/%d'), short_uid())
    def get_remaining_time_in_millis(self):