code: @Override
  	public List<ValidationResult> validate(Parameters args) {
  		if (_schema != null)
  			return _schema.validate(args);
  
  		return new ArrayList<ValidationResult>();
  	}
docs: Validates the command Parameters args before execution using the defined
  schema.
  
  @param args the parameters (arguments) to validate using this command's
  schema.
  @return a list ValidationResults or an empty list (if no schema is set).
  
  @see Parameters
  @see ValidationResult