2.2.x fix npe (#3085)

* fix: fix npe in routing and reverse the flag in observeListeners

* refactor: route -> routing

spring-cloud-alibaba-docs/src/main/asciidoc-zh/governance.adoc

@@ -99,7 +99,7 @@ spring:
 2.配置当没有路由规则时的负载均衡算法(以随机负载均衡算法为例)
 如果没有配置，使用ribbon默认的负载均衡算法ZoneAvoidanceRule
 ----
-spring.cloud.governance.routeing.rule=RandomRule
+spring.cloud.governance.routing.rule=RandomRule
 ----
 
 在引入Istio配置转换模块的前提下，标签路由模块支持对以下几种请求的元信息做路由

spring-cloud-alibaba-docs/src/main/asciidoc/governance.adoc

@@ -90,7 +90,7 @@ If you use Spring Cloud Alibaba Governance Label Routing in your project, You ne
 2.Configure a load balance algorithm when there are no routing rules (RandomRule algorithm as an example)
 If no configuration,use default ribbon load balance algorithm ZoneAvoidanceRule.
 ----
-spring.cloud.governance.routeing.rule=RandomRule
+spring.cloud.governance.routing.rule=RandomRule
 ----
 
 With the introduction of Istio Resource Transform module, the label routing module supports routing of the following types of request meta-information:

spring-cloud-alibaba-examples/governance-example/label-routing-example/consumer-example/src/main/resources/application.properties

@@ -5,4 +5,4 @@ spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
 spring.cloud.nacos.discovery.fail-fast=true
 spring.cloud.nacos.username=nacos
 spring.cloud.nacos.password=nacos
-#spring.cloud.governance.router.rule=RandomRule
+#spring.cloud.governance.routing.rule=RandomRule

spring-cloud-alibaba-examples/governance-example/label-routing-example/readme-zh.md

@@ -32,7 +32,7 @@
 2.配置当没有路由规则时的负载均衡算法(以随机负载均衡算法为例)
 如果没有配置，使用ribbon默认的负载均衡算法ZoneAvoidanceRule
 ```yaml
-spring.cloud.governance.routeing.rule=RandomRule
+spring.cloud.governance.routing.rule=RandomRule
 ```
 
 ### 应用启动

spring-cloud-alibaba-examples/governance-example/label-routing-example/readme.md

@@ -34,7 +34,7 @@ In the future, more components such as RestTemplate, Spring Cloud LoadBalancer a
 2.Configure a load balance algorithm when there are no routing rules (RandomRule algorithm as an example)
 If no configuration,use default ribbon load balance algorithm ZoneAvoidanceRule.
 ```yaml
-spring.cloud.governance.routeing.rule=RandomRule
+spring.cloud.governance.routing.rule=RandomRule
 ```
 
 ### Application Start

spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-governance-routing/src/main/java/com/alibaba/cloud/routing/RoutingProperties.java

@@ -16,6 +16,11 @@
 
 package com.alibaba.cloud.routing;
 
+import javax.annotation.PostConstruct;
+
+import com.alibaba.cloud.commons.lang.StringUtils;
+import com.alibaba.cloud.routing.util.LoadBalanceUtil;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -28,13 +33,20 @@ public class RoutingProperties {
 	/**
 	 * Properties prefix.
 	 */
-	public static final String PROPERTY_PREFIX = "spring.cloud.governance.router";
+	public static final String PROPERTY_PREFIX = "spring.cloud.governance.routing";
 
 	/**
 	 * Load Balance Rule.
 	 */
 	private String rule;
 
+	@PostConstruct
+	public void init() {
+		if (StringUtils.isEmpty(rule)) {
+			rule = LoadBalanceUtil.ZONE_AVOIDANCE_RULE;
+		}
+	}
+
 	public String getRule() {
 		return rule;
 	}

spring-cloud-alibaba-starters/spring-cloud-starter-xds-adapter/src/main/java/com/alibaba/cloud/governance/istio/PilotExchanger.java

@@ -56,7 +56,7 @@ public class PilotExchanger {
 			return;
 		}
 		Set<String> resourceName = ldsProtocol.getResourceNames();
-		if (CollectionUtils.isEmpty(resourceName)) {
+		if (!CollectionUtils.isEmpty(resourceName)) {
 			rdsProtocol.observeResource(resourceName, this::observeRoutes);
 		}