private function applyVolume(ControllerInterface $controller): ControllerStateInterface
    {
        $this->speakers = [];
        foreach ($controller->getSpeakers() as $speaker) {
            $this->speakers[$speaker->getUuid()] = $speaker->getVolume();
        }

        return $this;
    }
private function applyVolume(ControllerInterface $controller): ControllerStateInterface
    {
        $this->speakers = [];
        foreach ($controller->getSpeakers() as $speaker) {
            $this->speakers[$speaker->getUuid()] = $speaker->getVolume();
        }

        return $this;
    }
private function applyVolume ( ControllerInterface $ controller ) : ControllerStateInterface { $ this -> speakers = [ ] ; foreach ( $ controller -> getSpeakers ( ) as $ speaker ) { $ this -> speakers [ $ speaker -> getUuid ( ) ] = $ speaker -> getVolume ( ) ; } return $ this ; }
Get the current volume of all the speakers in this group.

@param ControllerInterface $controller The Controller to grab the state of

@return $this
Get the current volume of all the speakers in this group .