anchor.diff:                      String.format("Invalid value '%s' for option '--p': " +
                               "value is not a prime number.", value));
           }
  +        prime = value;
       }
       // ...
   }
  
positive.code:         }
      }
  
      private void missing(List<?> list) {
          return list == null || list.isEmpty();
      }
  }
  
negative.code: ----
  @Command(name = "myapp", mixinStandardHelpOptions = true, version = "myapp 0.1")
  class MultiOptionValidationExample implements Runnable {
      @Option(names="--xml") List<File> xmlFiles;
      @Option(names="--csv") List<File> csvFiles;
      @Option(names="--json") List<File> jsonFiles;
  
      @Spec CommandSpec spec; // injected by picocli
  
  