code: static public function getDefaultValue($name) {
          if (!static::getInstance()->defaultValues) {
              static::getInstance()->defaultValues = static::getAllDefaultValues();
          }
          if (array_has(static::getInstance()->defaultValues, $name)) {
              if (static::getInstance()->defaultValues[$name] instanceof \Closure) {
                  static::getInstance()->defaultValues[$name] = static::getInstance()->defaultValues[$name]();
              }
              return static::getInstance()->defaultValues[$name];
          }
          return null;
      }
docs: Get default value for setting $name
  @param string $name
  @return mixed