fix: verify connection is not a stale writer in the monitor (#1322)

Author: karenc-bq

wrapper/src/main/java/software/amazon/jdbc/hostlistprovider/monitoring/ClusterTopologyMonitorImpl.java

@@ -868,6 +868,18 @@ public void run() {
               connection = null;
             }
 
+            if (!StringUtils.isNullOrEmpty(writerId)) {
+              try {
+                if (this.servicesContainer.getPluginService().getHostRole(connection) != HostRole.WRITER) {
+                  // The first connection after failover may be stale.
+                  writerId = null;
+                }
+              } catch (SQLException e) {
+                // Invalid connection, retry.
+                continue;
+              }
+            }
+
             if (!StringUtils.isNullOrEmpty(writerId)) {
               // this prevents closing connection in finally block
               if (!this.monitor.nodeThreadsWriterConnection.compareAndSet(null, connection)) {