[fix] plugin/circuitbreaker/composite/rule.go

- 修复sortCircuitBreakerRules函数中rule.RuleMatcher.Destination.Method在rule类型为SERVICE或INSTANCE时为nil的问题。

plugin/circuitbreaker/composite/rule.go

@@ -210,18 +210,18 @@ func sortCircuitBreakerRules(rules []*fault_tolerance.CircuitBreakerRule) []*fau
 		// 1. compare destination service
 		destNamespace1 := rule1.RuleMatcher.Destination.Namespace
 		destService1 := rule1.RuleMatcher.Destination.Service
-		destMethod1 := rule1.RuleMatcher.Destination.Method.Value.Value
 
 		destNamespace2 := rule2.RuleMatcher.Destination.Namespace
 		destService2 := rule2.RuleMatcher.Destination.Service
-		destMethod2 := rule2.RuleMatcher.Destination.Method.Value.Value
 
 		svcResult := compareService(destNamespace1, destService1, destNamespace2, destService2)
 		if svcResult != 0 {
 			return svcResult < 0
 		}
 		if rule1.Level == rule2.Level {
 			if rule1.Level == fault_tolerance.Level_METHOD {
+				destMethod1 := rule1.RuleMatcher.Destination.Method.Value.Value
+				destMethod2 := rule2.RuleMatcher.Destination.Method.Value.Value
 				methodResult := compareStringValue(destMethod1, destMethod2)
 				if methodResult != 0 {
 					return methodResult < 0