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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)
```


DO_USE_DOCKER = None
JSON_START_CHAR_MAP = {
    list: ('[',),
    tuple: ('[',),
    dict: ('{',),
    str: ('"',),
    bytes: ('"',),
    bool: ('t', 'f'),
    type(None): ('n',),
    int: ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9'),
    float: ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9')
}
POSSIBLE_JSON_TYPES = (str, bytes)
JSON_START_TYPES = tuple(set(JSON_START_CHAR_MAP.keys()) - set(POSSIBLE_JSON_TYPES))
JSON_START_CHARS = tuple(set(functools.reduce(lambda x, y: x + y, JSON_START_CHAR_MAP.values())))
SQS_LISTENER_THREAD = {}
SQS_POLL_INTERVAL_SEC = 1
LAMBDA_EXECUTOR = lambda_executors.AVAILABLE_EXECUTORS.get(config.LAMBDA_EXECUTOR, lambda_executors.DEFAULT_EXECUTOR)
IAM_POLICY_VERSION = '2012-10-17'
CHECK_HANDLER_ON_CREATION = False
BUCKET_MARKER_LOCAL = '__local__'
class LambdaRegion(RegionBackend):
    def __init__(self):
        
        self.lambdas = {}
        
        self.code_signing_configs = {}
        
        self.event_source_mappings = []
class ClientError(Exception):