private Collection<Subchannel> getSubchannels() {
        return subchannels.values();
    }
Updates picker with the list of active subchannels (state == READY).
shenyu-plugin/shenyu-plugin-proxy/shenyu-plugin-rpc/shenyu-plugin-grpc/src/main/java/org/apache/shenyu/plugin/grpc/loadbalance/AbstractLoadBalancer.java