NotEmpty (ConfNG 1.1.0 API)

```
@Documented
@Retention(RUNTIME)
@Target(FIELD)
public @interface NotEmpty
```
Marks a configuration key as requiring a non-empty value.
When applied to a ConfNGKey enum constant, validation will fail if the configuration value is empty (blank string) or contains only whitespace.

Note: This is different from Required - a value can be present but empty. Use both annotations together if you want to require a non-empty value.

Example usage:
```
{@code
 public enum MyConfig implements ConfNGKey {
```
Since:

1.1.0

Author:

Bharat Kumar Malviya, GitHub: github.com/imBharatMalviya

See Also:

Required, ConfigValidator

- Optional Element Summary
  
  Optional Elements
  Modifier and Type Optional Element Description
  
  String message
  Custom error message to use when validation fails.

- Element Detail
  - message
```
String message
```
    Custom error message to use when validation fails. If empty, a default message will be generated.
    
    Returns:
    
    the custom error message
    
    Default:
    
    ""