public function handleCapabilities(
        \Erebot\Interfaces\EventHandler $handler,
        \Erebot\Event\ServerCapabilities $event
    ) {
        $module = $event->getModule();
        $validMappings  = array(
            // This is already the default value, but we still define it
            // in case setCollator() was called to change the default.
            'rfc1459'           => '\\Erebot\\IrcCollator\\RFC1459',
            'strict-rfc1459'    => '\\Erebot\\IrcCollator\\StrictRFC1459',
            'ascii'             => '\\Erebot\\IrcCollator\\ASCII',
        );
        $caseMapping    = strtolower($module->getCaseMapping());
        if (in_array($caseMapping, array_keys($validMappings))) {
            $cls = $validMappings[$caseMapping];
            $this->collator = new $cls();
        }
    }