diff --git a/build.gradle b/build.gradle
index 197cc1c..eefa89f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,9 +2,7 @@ plugins {
     id 'java'
     id 'java-library'
 }
-
 apply from: '../spotless.gradle'
-
 repositories {
     mavenCentral()
 }
diff --git a/src/main/java/org/bdware/sc/event/EventRecorder.java b/src/main/java/org/bdware/sc/event/EventRecorder.java
index 4fcf8ef..31af1c7 100644
--- a/src/main/java/org/bdware/sc/event/EventRecorder.java
+++ b/src/main/java/org/bdware/sc/event/EventRecorder.java
@@ -53,7 +53,7 @@ public class EventRecorder {
     }
 
     public void createCheckPoint(Map<String, Set<String>> topic2cIds,
-                                 Map<String, IEventConsumer> id2Consumers) {
+            Map<String, IEventConsumer> id2Consumers) {
         CheckPoint cp = new CheckPoint(topic2cIds, id2Consumers);
         synchronized (latestEvent) {
             if (!latestEvent.isCp()) {
@@ -79,8 +79,11 @@ public class EventRecorder {
         String key = KeyValueRocksDBUtil.instance.getValue(dbName, LATEST_EVENT_KEY);
         latestEvent.set(key);
         CheckPoint cp = new CheckPoint();
-        Type topic2cIdsType = TypeToken.getParameterized(ConcurrentHashMap.class, String.class,
-                TypeToken.getParameterized(Set.class, String.class).getType()).getType();
+        Type topic2cIdsType =
+                TypeToken
+                        .getParameterized(ConcurrentHashMap.class, String.class,
+                                TypeToken.getParameterized(Set.class, String.class).getType())
+                        .getType();
         // retrieving transactions from database
         while (null != key && !key.isEmpty()) {
             String json = KeyValueRocksDBUtil.instance.getValue(dbName, key);
@@ -92,14 +95,16 @@ public class EventRecorder {
                 if (json.startsWith("cp")) {
                     // create check point by the transaction and stop retrieving
                     JsonObject data = JsonUtil.parseStringAsJsonObject(json.substring(2));
-                    cp.topic2cIds = JsonUtil.fromJson(data.get("topic2cIds").toString(), topic2cIdsType);
+                    cp.topic2cIds =
+                            JsonUtil.fromJson(data.get("topic2cIds").toString(), topic2cIdsType);
                     JsonObject id2Consumers = data.getAsJsonObject("id2Consumers");
                     for (String k : id2Consumers.keySet()) {
                         JsonObject consumer = id2Consumers.getAsJsonObject(k);
                         if (!consumer.has("type")) {
                             continue;
                         }
-                        ConsumerType type = ConsumerType.valueOf(consumer.get("type").getAsString());
+                        ConsumerType type =
+                                ConsumerType.valueOf(consumer.get("type").getAsString());
                         switch (type) {
                             case Contract:
                                 cp.id2Consumers.put(k,
@@ -144,7 +149,8 @@ public class EventRecorder {
             // if empty, return the check point
             latestEvent.setCp(true);
         } else {
-            // on the base of old check point, process following sub or unsub events to recover registry
+            // on the base of old check point, process following sub or unsub events to recover
+            // registry
             while (!stack.empty()) {
                 Object record = stack.pop();
                 if (record instanceof CheckPoint) {
@@ -154,15 +160,19 @@ public class EventRecorder {
                     IEventConsumer consumer = broker.parseConsumer(tran.content);
                     switch (tran.type) {
                         case SUBSCRIBE:
-                            if (!broker.subInReg(tran.topic, consumer, cp.topic2cIds, cp.id2Consumers)) {
+                            if (!broker.subInReg(tran.topic, consumer, cp.topic2cIds,
+                                    cp.id2Consumers)) {
                                 LOGGER.warn("record damaged! " + key);
-                                LOGGER.debug("record damaged! " + key + ": " + JsonUtil.toJson(tran));
+                                LOGGER.debug(
+                                        "record damaged! " + key + ": " + JsonUtil.toJson(tran));
                             }
                             break;
                         case UNSUBSCRIBE:
-                            if (!broker.unsubInReg(tran.topic, consumer, cp.topic2cIds, cp.id2Consumers)) {
+                            if (!broker.unsubInReg(tran.topic, consumer, cp.topic2cIds,
+                                    cp.id2Consumers)) {
                                 LOGGER.warn("record damaged! " + key);
-                                LOGGER.debug("record damaged! " + key + ": " + JsonUtil.toJson(tran));
+                                LOGGER.debug(
+                                        "record damaged! " + key + ": " + JsonUtil.toJson(tran));
                             }
                         default:
                             break;
@@ -224,7 +234,7 @@ public class EventRecorder {
         }
 
         public CheckPoint(Map<String, Set<String>> topic2cIds,
-                          Map<String, IEventConsumer> id2Consumers) {
+                Map<String, IEventConsumer> id2Consumers) {
             this.topic2cIds = topic2cIds;
             this.id2Consumers = id2Consumers;
         }