[ISSUE-#4631] Free credential instance when serverHttpAgent shutdown. (#4634)

* free credential instance when serverHttpAgent shutdown.

* free credential instance when namingProxy shutdown.

* unify the code place

* cancel timer when CredentialWatcher stop

* ignore PMD.AvoidUseTimerRule.

client/src/main/java/com/alibaba/nacos/client/config/http/ServerHttpAgent.java

@@ -453,6 +453,7 @@ public class ServerHttpAgent implements HttpAgent {
         LOGGER.info("{} do shutdown begin", className);
         ThreadUtils.shutdownThreadPool(executorService, LOGGER);
         ConfigHttpClientManager.getInstance().shutdown();
+        SpasAdapter.freeCredentialInstance();
         LOGGER.info("{} do shutdown stop", className);
     }
     

client/src/main/java/com/alibaba/nacos/client/config/impl/SpasAdapter.java

@@ -74,6 +74,10 @@ public class SpasAdapter {
         return CredentialService.getInstance().getCredential().getAccessKey();
     }
     
+    public static void freeCredentialInstance() {
+        CredentialService.freeInstance();
+    }
+    
     /**
      * Sign with hmac SHA1 encrtpt.
      *

client/src/main/java/com/alibaba/nacos/client/identify/CredentialWatcher.java

@@ -53,7 +53,6 @@ public class CredentialWatcher {
     
     private final ScheduledExecutorService executor;
     
-    @SuppressWarnings("PMD.AvoidUseTimerRule")
     public CredentialWatcher(String appName, CredentialService serviceInstance) {
         this.appName = appName;
         this.serviceInstance = serviceInstance;

client/src/main/java/com/alibaba/nacos/client/naming/net/NamingProxy.java

@@ -719,6 +719,7 @@ public class NamingProxy implements Closeable {
         NAMING_LOGGER.info("{} do shutdown begin", className);
         ThreadUtils.shutdownThreadPool(executorService, NAMING_LOGGER);
         NamingHttpClientManager.getInstance().shutdown();
+        SpasAdapter.freeCredentialInstance();
         NAMING_LOGGER.info("{} do shutdown stop", className);
     }
 }