code: public static LoadBalancer getLoadBalancer(ConsumerBootstrap consumerBootstrap) {
          try {
              String loadBalancer = consumerBootstrap.getConsumerConfig().getLoadBalancer();
              ExtensionClass<LoadBalancer> ext = ExtensionLoaderFactory
                  .getExtensionLoader(LoadBalancer.class).getExtensionClass(loadBalancer);
              if (ext == null) {
                  throw ExceptionUtils.buildRuntime("consumer.loadBalancer",
                      loadBalancer, "Unsupported loadBalancer of client!");
              }
              return ext.getExtInstance(new Class[] { ConsumerBootstrap.class }, new Object[] { consumerBootstrap });
          } catch (SofaRpcRuntimeException e) {
              throw e;
          } catch (Throwable e) {
              throw new SofaRpcRuntimeException(e.getMessage(), e);
          }
      }
docs: 根据名字得到负载均衡器
  
  @param consumerBootstrap 服务订阅者配置
  @return LoadBalancer