AsyncStep (HAL :: Ballroom 3.6.14.Final API)

```
public interface AsyncStep<C>
```
Mixin interface for wizard steps which need an asynchronous implementation for the cancel, back and next workflow.

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method	Description
`default void`	`onBack(C context, WorkflowCallback callback)`	Called before the previous step is shown.
`default void`	`onCancel(C context, WorkflowCallback callback)`	Called when this step is canceled.
`default void`	`onNext(C context, WorkflowCallback callback)`	Called before the next step is shown.

- Method Detail
  - onCancel
```
default void onCancel(C context,
                      WorkflowCallback callback)
```
    Called when this step is canceled.
    The default implementation calls WorkflowCallback.proceed().
    
    Parameters:
    
    context - the current context
    
    callback - call WorkflowCallback.proceed() if we can cancel, do nothing otherwise
  - onBack
```
default void onBack(C context,
                    WorkflowCallback callback)
```
    Called before the previous step is shown. The method is called no matter if there's a previous step!
    The default implementation calls WorkflowCallback.proceed().
    
    Parameters:
    
    context - the current context
    
    callback - call WorkflowCallback.proceed() if we can navigate to the previous step, do nothing otherwise
  - onNext
```
default void onNext(C context,
                    WorkflowCallback callback)
```
    Called before the next step is shown. The method is called no matter if there's a next step!
    The default implementation calls WorkflowCallback.proceed().
    
    Parameters:
    
    context - the current context
    
    callback - call WorkflowCallback.proceed() if we can navigate to the next step, do nothing otherwise