anchor.diff:      var y = 0
   
       @Spec lateinit var spec: CommandSpec
  -    
  +
       override fun run() {
           val pr: ParseResult = spec.commandLine().parseResult
   
  
positive.code: }
  ----
  
  For the above group, only one of the options can be specified. Any other combination of options, or the absence of options, is invalid.
  
  CAUTION: Picocli will not initialize the `@ArgGroup`-annotated field
  
negative.code: }
  ----
  
  .Kotlin
  [source,kotlin,role="secondary"]
  ----
  class BadGroup {
      @Option(names = ["-x"], description = ["Default: \${DEFAULT-VALUE}"])
      var x = 123 // value not found until `BadGroup` is instantiated
  }
  
  @Command(name = "bad", description = ["usage help shows wrong default value"])
  class BadExample {
      @ArgGroup
      lateinit var badGroup: BadGroup
  }
  
  fun main(args: Array<String>) {
      CommandLine(BadExample()).usage(System.out)
  }
  ----
  
  When the default value is defined in the field declaration and not in the annotation, usage help for the options in the group incorrectly shows `null` as the default value:
  
  ----
  