code: public static boolean isEnable() {
          boolean enable = "sofaTracer".equals(RpcConfigs.getStringValue(RpcOptions.DEFAULT_TRACER));
          if (enable) {
              try {
                  ClassUtils.forName("javax.ws.rs.container.ContainerRequestFilter");
                  ClassUtils.forName("javax.ws.rs.container.ContainerResponseFilter");
                  ClassUtils.forName("org.jboss.resteasy.core.interception.PostMatchContainerRequestContext");
                  ClassUtils.forName("org.jboss.resteasy.plugins.server.netty.NettyHttpRequest");
                  ClassUtils.forName("org.jboss.resteasy.plugins.server.netty.NettyHttpResponse");
              } catch (Exception e) {
                  return false;
              }
          }
          return enable;
      }
docs: 是否启动Tracer
  
  @return 是否开启