public function addGroup(GroupInterface $group): self
    {
        if (!$group instanceof Production) {
            throw new Exception('Group type not supported.');
        }
        $this->groups[] = $group;

        return $this;
    }
public function addGroup(GroupInterface $group): self
    {
        if (!$group instanceof Production) {
            throw new Exception('Group type not supported.');
        }
        $this->groups[] = $group;

        return $this;
    }
public function addGroup ( GroupInterface $ group ) : self { if ( ! $ group instanceof Production ) { throw new Exception ( 'Group type not supported.' ) ; } $ this -> groups [ ] = $ group ; return $ this ; }
Add group.

@param Production $group The production.

@return Event
Add group .