src/CoreBundle/EventListener/DcGeneral/Table/MetaModel/DcaCombineButtonListener.php
public function handle(GetOperationButtonEvent $event)
    {
        if (!$this->wantToHandle($event)) {
            return;
        }

        $command = $event->getCommand();
        if ($command->getName() == 'dca_combine') {
            $event->setHref(
                UrlBuilder::fromUrl($event->getHref())
                    ->setQueryParameter(
                        'id',
                        ModelId::fromValues('tl_metamodel_dca_combine', $event->getModel()->getId())->getSerialized()
                    )
                    ->getUrl()
            );
        }
    }
public function handle(GetOperationButtonEvent $event)
    {
        if (!$this->wantToHandle($event)) {
            return;
        }

        $command = $event->getCommand();
        if ($command->getName() == 'dca_combine') {
            $event->setHref(
                UrlBuilder::fromUrl($event->getHref())
                    ->setQueryParameter(
                        'id',
                        ModelId::fromValues('tl_metamodel_dca_combine', $event->getModel()->getId())->getSerialized()
                    )
                    ->getUrl()
            );
        }
    }
Clear the button if the User is not admin.

@param GetOperationButtonEvent $event The event.

@return void