TooltipBodyCallback (Charba - J2CL and GWT charts library based on CHART.JS)

All Known Implementing Classes:

AbstractTooltipBodyCallback
```
public interface TooltipBodyCallback
```
The tooltip label configuration is nested below the tooltip configuration using the callbacks key.
The tooltip has the following callbacks for providing text.
All functions must return either a string or an array of strings. Arrays of strings are treated as multiple lines of text.
This interface takes care about labels to apply to the body.

Author:

Andrea "Stock" Stocchero

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method	Description
`default List<String>`	`onAfterBody(IsChart chart, List<TooltipItem> items)`	Returns text to render after the body section. If returns `null` or empty list, it will be ignored.
`default List<String>`	`onBeforeBody(IsChart chart, List<TooltipItem> items)`	Returns text to render before the body section. If returns `null` or empty list, it will be ignored.

- Method Detail
  - onBeforeBody
```
default List<String> onBeforeBody(IsChart chart,
                                  List<TooltipItem> items)
```
    Returns text to render before the body section.
    If returns null or empty list, it will be ignored.
    
    Parameters:
    
    chart - chart instance
    
    items - list of all tooltip items
    
    Returns:
    
    a list of labels to apply to the body.
  - onAfterBody
```
default List<String> onAfterBody(IsChart chart,
                                 List<TooltipItem> items)
```
    Returns text to render after the body section.
    If returns null or empty list, it will be ignored.
    
    Parameters:
    
    chart - chart instance
    
    items - list of all tooltips items
    
    Returns:
    
    a list of labels to apply to the body.