public function addOptionalResource($resource, $prefix = null)
    {
        $this->resources[] = [$resource, $prefix, false];

        return $this;
    }
public function addOptionalResource($resource, $prefix = null)
    {
        $this->resources[] = [$resource, $prefix, false];

        return $this;
    }
public function addOptionalResource ( $ resource , $ prefix = null ) { $ this -> resources [ ] = [ $ resource , $ prefix , false ] ; return $ this ; }
Add an optional resource to load configuration values from.

@param mixed       $resource
@param string|null $prefix   The prefix to give the values, if any
Add an optional resource to load configuration values from .