Refactoring a class / map of query parameters that are passed between layers
It's cleaner and possible to create types of Parameter class, such as CarParameter, MotoParameter, and use Spring type conversion. 

First your signature would become something like 

@RequestMapping(".../car/...")
public Journal createCarsJournal(@RequestParam CarParameter params) {
    return carsJCreator.create(params);
}

@RequestMapping(".../moto/...")
public Journal createMotosJournal(@RequestParam MotoParameter params) {
    return motosJCreator.create(params);
}


To build the customized conversion, check out Guide to Spring Type Conversions.