Spring Cloud AWS InstantiationException thrown when using @Autowire

I like the the ability to use constructors to add dependencies. Especially autowiring those dependencies.

e.g.

public class MyClass {
    private final Dependency dependency;

    @Autowired
    public MyClass(@Qualifier("bean-id") Dependency dependency) {
        this.dependency = dependency;
    }

}

What I'm finding is that the Spring Cloud AWS framework throws an "InstantiationException" if the "Dependency" class above happens to be a class which is passed to a Workflow worker and is missing a default, empty constructor.

concrete example:

public class MyClass {
    private final DependencyWorkflowClientExternalFactory clientFactory;

    @Autowired
    public MyClass(@Qualifier("bean-id") DependencyWorkflowClientExternalFactory clientFactory) {
        this.clientFactory = clientFactory;
    }
}

public class WorkflowInitializer {

    @Autowired
    private WorkflowWorker workflowWorker; //assume wired with correct credentials    

    public WorkflowInitialiser() {
         init();
    }

    public init() {
        workflowWorker.addWorkflowImplementationType(MyClass.class);
    }
}

the above fails with:

java.lang.InstantiationException: com.mypackage.MyClass
at java.lang.Class.newInstance(Class.java:359)

I have to do something like:

public class MyClass {
    @Autowired
    @Qualifier("bean-id")
    private Dependency dependency; 

    public MyClass() {
    }
}

The question is:

Is it possible in the current release of the Spring Cloud framework to use the @Autowire annotation on a constructor for a workflow client implementation? Or is it a requirement that the annotation is added to the instance field?

As a secondary question:

Why do ActivityWorkers take instances of an object but WorkflowWorkers take classes?