protected function setOptional($key, $value) {
        if (!$this->has($key))
            $this->set($key, $value);
    }
protected function setOptional($key, $value) {
        if (!$this->has($key))
            $this->set($key, $value);
    }
protected function setOptional ( $ key , $ value ) { if ( ! $ this -> has ( $ key ) ) $ this -> set ( $ key , $ value ) ; }
Sets a setting if it is not already set.
@param string $key
@param mixed $value
Sets a setting if it is not already set .