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"
		}
	}]
}
```

if runtime.startswith(LAMBDA_RUNTIME_PROVIDED):
        return 'bootstrap'
    delimiter = '.'
    if runtime.startswith(LAMBDA_RUNTIME_NODEJS):
        file_ext = '.js'
    elif runtime.startswith(LAMBDA_RUNTIME_GOLANG):
        file_ext = ''
    elif runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE2) or runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE21):
        file_ext = '.dll'
        delimiter = ':'
    elif runtime.startswith(LAMBDA_RUNTIME_RUBY):
        file_ext = '.rb'
    else:
        handler_name = handler_name.rpartition(delimiter)[0].replace(delimiter, os.path.sep)
        file_ext = '.py'
    return '%s%s' % (handler_name.split(delimiter)[0], file_ext)
def get_handler_function_from_name(handler_name, runtime=LAMBDA_DEFAULT_RUNTIME):
    
    if runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE2) or runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE21):
        return handler_name.split(':')[-1]
    else:
        return handler_name.split('.')[-1]
def error_response(msg, code=500, error_type='InternalFailure'):
    LOG.warning(msg)
    return aws_responses.flask_error_response(msg, code=code, error_type=error_type)
def get_zip_bytes(function_code):
    """Returns the ZIP file contents from a FunctionCode dict.
    :type function_code: dict