public function createCluster($projectId, $region, $cluster, array $optionalArgs = [])
    {
        $request = new CreateClusterRequest();
        $request->setProjectId($projectId);
        $request->setRegion($region);
        $request->setCluster($cluster);
        if (isset($optionalArgs['requestId'])) {
            $request->setRequestId($optionalArgs['requestId']);
        }

        return $this->startOperationsCall(
            'CreateCluster',
            $optionalArgs,
            $request,
            $this->getOperationsClient()
        )->wait();
    }