[#1568] rocketmq need enhance stability when commitlog broken

 增加非空判断，防止空指针异常,导致循环事务 check,增加test覆盖，修复编码格式

broker/src/main/java/org/apache/rocketmq/broker/transaction/queue/TransactionalMessageBridge.java

@@ -131,7 +131,7 @@ public class TransactionalMessageBridge {
                     this.brokerController.getBrokerStatsManager().incGroupGetSize(group, topic,
                         getMessageResult.getBufferTotalSize());
                     this.brokerController.getBrokerStatsManager().incBrokerGetNums(getMessageResult.getMessageCount());
-                    if ( foundList == null || foundList.size() == 0 ) {
+                    if (foundList == null || foundList.size() == 0) {
                         break;
                     }
                     this.brokerController.getBrokerStatsManager().recordDiskFallBehindTime(group, topic, queueId,