@Override
    public CompletableFuture<Endpoint> select(ClientRequestContext ctx, ScheduledExecutorService executor) {
        return selector.select(ctx, executor);
    }
Constructs a new {@link CompositeEndpointGroup} that merges all the given {@code endpointGroups}.
core/src/main/java/com/linecorp/armeria/client/endpoint/CompositeEndpointGroup.java