anchor.diff:          }
       }
   
  -    private void missing(List<?> list) {
  +    private boolean missing(List<?> list) {
           return list == null || list.isEmpty();
       }
   }
  
positive.code:                     String.format("Invalid value '%s' for option '--p': " +
                              "value is not a prime number.", value));
          }
      }
      // ...
  }
  
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
  
  