RequiredUnlessEnvironment

```
@Retention(RUNTIME)
@Target(FIELD)
public @interface RequiredUnlessEnvironment
```
An annotation that indicates that an option/arguments is required UNLESS a specific environment variable is set.
This is intended for situations where your options are being populated by default values taken from environment variables and you only require the option if a suitable default is not already provided by the environment.

If you have other requirement criteria then you may wish to use Required, RequiredOnlyIf, RequireSome or RequireOnlyOne instead.

Required Element Summary

Required Elements
Modifier and Type	Required Element	Description
`java.lang.String[]`	`variables`	Specifies the name(s) of the environment variable that when present renders the option not required

- Element Detail
  - variables
```
java.lang.String[] variables
```
    Specifies the name(s) of the environment variable that when present renders the option not required
    
    Returns:
    
    Name(s) of the environment variables