I have a setup where there is a node.js application that writes to a kinesis stream using putRecords for two items. The kinesis stream feeds a Lambda function that is configured with an eventSourceMapping with a batch size of 1. However, when I debug what the Records Kinesis feeds the lambda for an invocation, I see that the lambda is processing two records. Both of these records are on the same shard and have a sequence number which is pretty close.

The interesting thing is that if I switch the node.js published to use putRecord instead of putRecords, the kinesis records have a slightly farther apart sequence number and the lambda is fed the records individually.

The java code to configure the event source mapping
```
        AWSLambdaAsync lambdaClient = AWSResourceFactory.getLambdaClient();
        CreateEventSourceMappingRequest request = new CreateEventSourceMappingRequest();
        request.setEventSourceArn(kinesisArn);
        request.setFunctionName(functionName);
        request.setEnabled(true);
        request.setStartingPosition(EventSourcePosition.TRIM_HORIZON);
        request.setBatchSize(1);
        lambdaClient.createEventSourceMapping(request);
```

The localstack lambda output that shows multiple records being read at a time:

```
{
	"Records": [{
		"eventID": "shardId-000000000000:49593014281924840790139112603493819506073986345293840386",
		"eventSourceARN": "arn:aws:kinesis:us-east-1:000000000000:stream/MyStream",
		"kinesis": {
			"partitionKey": "ed0f756b97234f4fae9e3d1a886b8fbc",
			"data": "myData1",
			"sequenceNumber": "49593014281924840790139112603493819506073986345293840386"
		}
	}, {
		"eventID": "shardId-000000000000:49593014281924840790139112603495028431893600974468546562",
		"eventSourceARN": "arn:aws:kinesis:us-east-1:000000000000:stream/MyStream",
		"kinesis": {
			"partitionKey": "abee63a9299385699d65e89a290a9065",
			"data": "myData2",
			"sequenceNumber": "49593014281924840790139112603495028431893600974468546562"
		}
	}]
}
```

elif mapped.startswith(occurred):
        suffix = mapped[len(occurred):]
        return suffix[0] == '/'
    else:
        return False
def get_function_version(arn, version):
    func = arn_to_lambda.get(arn)
    return format_func_details(func, version=version, always_add_version=True)
def publish_new_function_version(arn):
    func_details = arn_to_lambda.get(arn)
    versions = func_details.versions
    last_version = func_details.max_version()
    versions[str(last_version + 1)] = {
        'CodeSize': versions.get('$LATEST').get('CodeSize'),
        'CodeSha256': versions.get('$LATEST').get('CodeSha256'),
        'Function': versions.get('$LATEST').get('Function'),
        'RevisionId': str(uuid.uuid4())
    }
    return get_function_version(arn, str(last_version + 1))
def do_list_versions(arn):
    return sorted([get_function_version(arn, version) for version in
                   arn_to_lambda.get(arn).versions.keys()], key=lambda k: str(k.get('Version')))
def do_update_alias(arn, alias, version, description=None):
    new_alias = {
        'AliasArn': arn + ':' + alias,
        'FunctionVersion': version,
        'Name': alias,
        'Description': description or '',
        'RevisionId': str(uuid.uuid4())