code: @PostDeploy
    public void onDeploymentFinished(ProcessEngine processEngine) {
      if (processEngine.getRuntimeService().createProcessInstanceQuery().processDefinitionKey(PROCESS_DEFINITION_KEY).count()==0) {
        
        Order order = new Order()
          .addItem(new Item().setId("01").setText("First Item"))
          .addItem(new Item().setId("02").setText("Second Item"))
          .addItem(new Item().setId("03").setText("Third Item"));
        
        processEngine.getRuntimeService().startProcessInstanceByKey( //
            PROCESS_DEFINITION_KEY, //
            Variables.createVariables().putValueTyped( //
                ProcessVariables.VAR_NAME_ORDER, //
                Variables.objectValue(order).serializationDataFormat(SerializationDataFormats.JSON).create()));
      }
    }
docs: In a @PostDeploy Hook you can interact with the process engine and access
  the processes the application has deployed.