using apache camel, smooks and flatpack

Question

I am writing a route using camel and smooks, with the producer as a JPA repository that produces a List of JPA Objects, which I need to send to an sftp server as a fixed width file.

Here is what I think is required for this to occur

1. The repository which uses JPA to produce a list of Objects (I have this)
2. A smooks to flatpack mapping which takes the xml version of the list mentioned above, and transforms it into a fixed width file
3. A camel route which starts with the repository and ends with the file being send via sftp:

Here is the code I have for this:

public class RetirementRoute extends RouteBuilder {

    @Override
    public void configure() throws Exception {

        onException(Throwable.class)
                .maximumRedeliveries(3)
                .useExponentialBackOff()
                .backOffMultiplier(4)
                .logRetryAttempted(true)
                .handled(true)
                .log(LoggingLevel.ERROR, "Error transmitting file to miliman")
                .to("log:org.fuwt?level=ERROR&showAll=true");

        //define the fixed width mapping
        FlatpackDataFormat df = new FlatpackDataFormat();
        df.setDefinition(new ClassPathResource("META-INF/smooks/fuintegration/retirement-fixed-width-mapping.xml"));
        df.setFixed(true);
        df.setIgnoreFirstRecord(false);

        from("bean:retirementRepository?method=getRetirementMembers")
                .to("log:org.fuwt?level=INFO")
                .transacted("CRM_PROPAGATION_REQUIRED")
                .routeId("retirement_member_exchange")
                .aggregate(property("CamelCreatedTimestamp"), new RetirementAggregationStrategy()).completionFromBatchConsumer()
                .marshal(df).log("log:org.fuwt?level=ERROR&showAll=true")
                .to("file://Users/smohamed/tests/?fileName=marshal.test.txt");
    }
}

However, when I run a unit test, I get the following error:

ArrayList cannot be converted to RetirementMember

which I think means that flatpack doesn't know what to do with the list, and needs to work on an object per object basis.

Hence, what I'm looking for is a smooks mapping similar to freemaker template, but instead of a freemaker template, I want to use flatpack's columns definitions:

<?xml version='1.0'?>  
<!DOCTYPE PZMAP SYSTEM "flatpack.dtd" >  
<PZMAP>  
    <COLUMN name="ssn" length="11" />  
    <COLUMN name="lastName" length="20" />  
    <COLUMN name="firstName" length="15" />  
</PZMAP>

What is the best way to go about this? There isn't much documentation available and I've been searching for weeks

thanks

Sam