final EventLoop getOrAcquireEventLoop() {
        if (eventLoop != null) {
            return eventLoop;
        } else {
            return CommonPools.workerGroup().next();
        }
    }
Returns the {@link EventLoop} set via {@link #eventLoop(EventLoop)} or acquires a random
{@link EventLoop} from {@link CommonPools#workerGroup()}.
core/src/main/java/com/linecorp/armeria/client/endpoint/dns/DnsEndpointGroupBuilder.java