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

All Known Implementing Classes:

AnnotationEnvelop, BaseEnvelop, CallbacksEnvelop, ChartEnvelop, ConfigurationEnvelop, DataEnvelop, DataLabelsEnvelop, ImmutableEnvelop, ItemsEnvelop, LabelsEnvelop, OptionsEnvelop, PluginsEnvelop
```
public interface Envelop
```
This is the interface to map the envelop.
It adds helpful methods to check the envelop.

Author:

Andrea "Stock" Stocchero

Method Summary

All Methods Static Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`static <T extends Envelop> T`	`checkAndGetIfValid(T envelop)`	Checks if envelop passed as argument is not `null` and its content is not `null` as well. If not, throw a `IllegalArgumentException`.
`static void`	`checkIfValid(Envelop envelop)`	Checks if envelop passed as argument is not `null` and its content is not `null` as well. If not, throw a `IllegalArgumentException`.
`boolean`	`hasContent()`	Returns `true` if the content of envelop is not `null`.
`boolean`	`isNullable()`	Returns `true` if the content of envelop can be `null`.
`static boolean`	`isValid(Envelop envelop)`	Returns `true` if envelop passed as argument is not `null` and its content is not `null` as well.

- Method Detail
  - isValid
```
static boolean isValid(Envelop envelop)
```
    Returns true if envelop passed as argument is not null and its content is not null as well.
    
    Parameters:
    
    envelop - envelop to be checked
    
    Returns:
    
    true if envelop passed as argument is not null and its content is not null as well.
  - checkIfValid
```
static void checkIfValid(Envelop envelop)
```
    Checks if envelop passed as argument is not null and its content is not null as well.
    If not, throw a IllegalArgumentException.
    
    Parameters:
    
    envelop - envelop to be checked
  - checkAndGetIfValid
```
static <T extends Envelop> T checkAndGetIfValid(T envelop)
```
    Checks if envelop passed as argument is not null and its content is not null as well.
    If not, throw a IllegalArgumentException.
    
    Type Parameters:
    
    T - type of envelop
    
    Parameters:
    
    envelop - key to be checked
    
    Returns:
    
    the same key passed as argument
  - hasContent
```
boolean hasContent()
```
    Returns true if the content of envelop is not null.
    
    Returns:
    
    true if the content of envelop is not null
  - isNullable
```
boolean isNullable()
```
    Returns true if the content of envelop can be null.
    
    Returns:
    
    true if the content of envelop can be null