Return file content from Camel route using exchange

Im using FluentProducerTemplate to send some data into Camel route and getting back hardcoded string message "Hello". Now I want Camel route to return data from text or json file which is stored locally. I couldn't find in a documentation how route should return the file content. I assume it should be something as exchange.getIn().setBody(<declare path>) but Im not sure how to do/declare it. I would have that file in a project's IDE folder/package dataOut/data.txt.

@EndpointInject
private FluentProducerTemplate producer;

public String getDataFromRoute(Employee employee){
    String strData = producer.withBody(employee)
           .to("direct:invokeRoute")
           .request(String.class);
    return strData;      
}

@Override
public void configure() throws Exception {
     from("direct:invokeRoute")
            .process(exchange -> {
                 exchange.getIn().setBody("Hallo")
        });
}