code: public function getRuleConfiguration($rule)
      {
          if (!$this->hasRule($rule)) {
              throw new \InvalidArgumentException(sprintf('Rule "%s" is not in the set.', $rule));
          }
  
          if (true === $this->rules[$rule]) {
              return null;
          }
  
          return $this->rules[$rule];
      }
docs: {@inheritdoc}