Spring Boot Webapp - Creating a Flowable workflow

I setup Flowable into my existing spring boot app using “flowable-spring-boot-starter-rest-api” dependency. I was able to run through a basic test flow defined in the documentation, but then when it comes to converting an existing workflow into a Flowable structure I am struggling.

Currently I have a controller class that calls three service classes in sequence each responsible for different set of tasks with the same set of objects. I started out by creating a Flowable specific service class that implements “JavaDelegate” which in turn is supposed to call my original autowired service class. And then I defined the Flowable specific service class against a service task in my bpmn xml. Now during execution, the flow reaches the new service class but finds the autowired class instance as null. What am I missing here?

This is the first time I am using Flowable and I am not even sure if I can use Flowable for what I am trying to intend to.