diff --git a/.gitignore b/.gitignore
index f7bcdbf5..05e7e3ad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -81,3 +81,4 @@ hs_err_pid*
 .mtj.tmp/
 # blueJ files
 *.ctxt
+.flattened-pom.xml
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/config/HugeConfig.java b/hugegraph-common/src/main/java/org/apache/hugegraph/config/HugeConfig.java
index b25153d4..17088ea3 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/config/HugeConfig.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/config/HugeConfig.java
@@ -186,11 +186,9 @@ private static Configuration loadConfigFile(File configFile) {
                 case "yml":
                 case "yaml":
                     Parameters params = new Parameters();
-                    FileBasedConfigurationBuilder<FileBasedConfiguration>
-                    builder = new FileBasedConfigurationBuilder(
-                                  YAMLConfiguration.class)
-                                  .configure(params.fileBased()
-                                  .setFile(configFile));
+                    FileBasedConfigurationBuilder<FileBasedConfiguration> builder =
+                            new FileBasedConfigurationBuilder(YAMLConfiguration.class)
+                                    .configure(params.fileBased().setFile(configFile));
                     config = builder.getConfiguration();
                     break;
                 case "xml":
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/config/OptionChecker.java b/hugegraph-common/src/main/java/org/apache/hugegraph/config/OptionChecker.java
index 8676702a..0e795ff1 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/config/OptionChecker.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/config/OptionChecker.java
@@ -24,8 +24,6 @@
 import java.util.HashSet;
 import java.util.List;
 
-import javax.annotation.Nullable;
-
 import org.apache.commons.lang3.StringUtils;
 
 import com.google.common.base.Predicate;
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/func/TriFunction.java b/hugegraph-common/src/main/java/org/apache/hugegraph/func/TriFunction.java
index d84c26f3..0e5fbb46 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/func/TriFunction.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/func/TriFunction.java
@@ -19,7 +19,7 @@
 
 package org.apache.hugegraph.func;
 
-public interface TriFunction <T1, T2, T3, R> {
+public interface TriFunction<T1, T2, T3, R> {
 
     R apply(T1 v1, T2 v2, T3 v3);
 }
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/perf/PerfUtil.java b/hugegraph-common/src/main/java/org/apache/hugegraph/perf/PerfUtil.java
index 39cface3..36b5c051 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/perf/PerfUtil.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/perf/PerfUtil.java
@@ -55,7 +55,7 @@
 public final class PerfUtil {
 
     private static final Logger LOG = Log.logger(PerfUtil.class);
-    private static final int DEFAUL_CAPATICY = 1024;
+    private static final int DEFAULT_CAPACITY = 1024;
 
     private static final ThreadLocal<PerfUtil> INSTANCE = new ThreadLocal<>();
 
@@ -69,8 +69,8 @@ public final class PerfUtil {
     private final Stopwatch root;
 
     private PerfUtil() {
-        this.stopwatches = new HashMap<>(DEFAUL_CAPATICY);
-        this.callStack = new LocalStack<>(DEFAUL_CAPATICY);
+        this.stopwatches = new HashMap<>(DEFAULT_CAPACITY);
+        this.callStack = new LocalStack<>(DEFAULT_CAPACITY);
         this.root = newStopwatch(Path.ROOT_NAME, Path.EMPTY);
     }
 
@@ -403,32 +403,32 @@ public String toECharts() {
         };
 
         BiConsumer<List<Stopwatch>, List<Stopwatch>> fillChildrenTotal =
-                                    (itemsOfLn, itemsOfLnParent) -> {
-            for (Stopwatch parent : itemsOfLnParent) {
-                List<Stopwatch> children = itemsOfLn.stream().filter(c -> {
-                    return c.parent().equals(parent.id());
-                }).collect(Collectors.toList());
+                (itemsOfLn, itemsOfLnParent) -> {
+                    for (Stopwatch parent : itemsOfLnParent) {
+                        List<Stopwatch> children = itemsOfLn.stream().filter(c -> {
+                            return c.parent().equals(parent.id());
+                        }).collect(Collectors.toList());
 
-                parent.fillChildrenTotal(children);
-            }
-        };
+                        parent.fillChildrenTotal(children);
+                    }
+                };
 
         BiConsumer<List<Stopwatch>, List<Stopwatch>> fillOther =
-                                    (itemsOfLn, itemsOfLnParent) -> {
-            for (Stopwatch parent : itemsOfLnParent) {
-                Stream<Stopwatch> children = itemsOfLn.stream().filter(c -> {
-                    return c.parent().equals(parent.id());
-                });
-                // Fill other cost
-                long sumCost = children.mapToLong(Stopwatch::totalCost).sum();
-                long otherCost = parent.totalCost() - sumCost;
-                if (otherCost > 0L) {
-                    Stopwatch other = newStopwatch("~", parent.id());
-                    other.totalCost(otherCost);
-                    itemsOfLn.add(other);
-                }
-            }
-        };
+                (itemsOfLn, itemsOfLnParent) -> {
+                    for (Stopwatch parent : itemsOfLnParent) {
+                        Stream<Stopwatch> children = itemsOfLn.stream().filter(c -> {
+                            return c.parent().equals(parent.id());
+                        });
+                        // Fill other cost
+                        long sumCost = children.mapToLong(Stopwatch::totalCost).sum();
+                        long otherCost = parent.totalCost() - sumCost;
+                        if (otherCost > 0L) {
+                            Stopwatch other = newStopwatch("~", parent.id());
+                            other.totalCost(otherCost);
+                            itemsOfLn.add(other);
+                        }
+                    }
+                };
 
         Map<Path, Stopwatch> items = this.stopwatches;
         Map<Integer, List<Stopwatch>> levelItems = new HashMap<>();
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/perf/Stopwatch.java b/hugegraph-common/src/main/java/org/apache/hugegraph/perf/Stopwatch.java
index 9d095c92..15f7a234 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/perf/Stopwatch.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/perf/Stopwatch.java
@@ -24,26 +24,35 @@
 public interface Stopwatch extends Cloneable {
 
     Path id();
+
     String name();
+
     Path parent();
 
     void startTime(long startTime);
+
     void endTime(long startTime);
 
     void lastStartTime(long startTime);
 
     long times();
+
     long totalTimes();
+
     long totalChildrenTimes();
 
     long totalCost();
+
     void totalCost(long otherCost);
 
     long minCost();
+
     long maxCost();
 
     long totalWasted();
+
     long totalSelfWasted();
+
     long totalChildrenWasted();
 
     void fillChildrenTotal(List<Stopwatch> children);
@@ -51,9 +60,11 @@ public interface Stopwatch extends Cloneable {
     Stopwatch copy();
 
     Stopwatch child(String name);
+
     Stopwatch child(String name, Stopwatch watch);
 
     boolean empty();
+
     void clear();
 
     default String toJson() {
@@ -97,11 +108,7 @@ public Path(Path parent, String name) {
             if (parent == EMPTY) {
                 this.path = name;
             } else {
-                int len = parent.length() + 1 + name.length();
-                StringBuilder sb = new StringBuilder(len);
-                sb.append(parent.path).append('/').append(name);
-
-                this.path = sb.toString();
+                this.path = parent.path + '/' + name;
             }
         }
 
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/rest/AbstractRestClient.java b/hugegraph-common/src/main/java/org/apache/hugegraph/rest/AbstractRestClient.java
index 0ccf1ad6..e6708c5c 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/rest/AbstractRestClient.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/rest/AbstractRestClient.java
@@ -19,7 +19,6 @@
 
 package org.apache.hugegraph.rest;
 
-import java.io.IOException;
 import java.net.URI;
 import java.security.KeyManagementException;
 import java.security.SecureRandom;
@@ -32,19 +31,14 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
+import javax.net.ssl.HostnameVerifier;
+import javax.net.ssl.HttpsURLConnection;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSession;
+import javax.net.ssl.TrustManager;
+import javax.net.ssl.X509TrustManager;
+
 import org.apache.commons.collections.MapUtils;
-import org.apache.hugegraph.util.E;
-import org.apache.hugegraph.util.ExecutorUtil;
-import jakarta.ws.rs.client.Client;
-import jakarta.ws.rs.client.ClientRequestContext;
-import jakarta.ws.rs.client.ClientRequestFilter;
-import jakarta.ws.rs.client.Entity;
-import jakarta.ws.rs.client.Invocation.Builder;
-import jakarta.ws.rs.client.WebTarget;
-import jakarta.ws.rs.core.MediaType;
-import jakarta.ws.rs.core.MultivaluedMap;
-import jakarta.ws.rs.core.Response;
-import jakarta.ws.rs.core.Variant;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.http.HttpHeaders;
@@ -55,6 +49,8 @@
 import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
 import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
 import org.apache.http.pool.PoolStats;
+import org.apache.hugegraph.util.E;
+import org.apache.hugegraph.util.ExecutorUtil;
 import org.glassfish.jersey.SslConfigurator;
 import org.glassfish.jersey.apache.connector.ApacheClientProperties;
 import org.glassfish.jersey.apache.connector.ApacheConnectorProvider;
@@ -69,12 +65,16 @@
 
 import com.google.common.collect.ImmutableMap;
 
-import javax.net.ssl.HostnameVerifier;
-import javax.net.ssl.HttpsURLConnection;
-import javax.net.ssl.SSLContext;
-import javax.net.ssl.SSLSession;
-import javax.net.ssl.TrustManager;
-import javax.net.ssl.X509TrustManager;
+import jakarta.ws.rs.client.Client;
+import jakarta.ws.rs.client.ClientRequestContext;
+import jakarta.ws.rs.client.ClientRequestFilter;
+import jakarta.ws.rs.client.Entity;
+import jakarta.ws.rs.client.Invocation.Builder;
+import jakarta.ws.rs.client.WebTarget;
+import jakarta.ws.rs.core.MediaType;
+import jakarta.ws.rs.core.MultivaluedMap;
+import jakarta.ws.rs.core.Response;
+import jakarta.ws.rs.core.Variant;
 
 public abstract class AbstractRestClient implements RestClient {
 
@@ -412,15 +412,14 @@ private Pair<Builder, Entity<?>> buildRequest(
 
     /**
      * parse user custom content-type, returns MediaType.APPLICATION_JSON_TYPE default.
-     * @param headers
-     * @return
+     * @param headers custom http header
      */
-    public static MediaType parseCustomContentType(MultivaluedMap<String, Object> headers) {
+    private static MediaType parseCustomContentType(MultivaluedMap<String, Object> headers) {
         String customContentType = null;
         if (MapUtils.isNotEmpty(headers) && headers.get("Content-Type") != null) {
-            Object contentTypeObj = headers.get("Content-Type");
-            if (contentTypeObj instanceof List) {
-                customContentType = ((List<?>) contentTypeObj).get(0).toString();
+            List<?> contentTypeObj = headers.get("Content-Type");
+            if (contentTypeObj != null && !contentTypeObj.isEmpty()) {
+                customContentType = contentTypeObj.get(0).toString();
             }
             return MediaType.valueOf(customContentType);
         }
@@ -546,7 +545,7 @@ private static class ConfigBuilder {
 
         private final ClientConfig config;
 
-        public ConfigBuilder() {
+        ConfigBuilder() {
             this.config = new ClientConfig();
         }
 
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/testutil/Assert.java b/hugegraph-common/src/main/java/org/apache/hugegraph/testutil/Assert.java
index 519d2053..5e09cb83 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/testutil/Assert.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/testutil/Assert.java
@@ -144,8 +144,7 @@ private static class NumberMatcher extends BaseMatcher<Object> {
         private final Number expected;
         private final Function<Integer, Boolean> cmp;
 
-        public NumberMatcher(Number expected, Function<Integer, Boolean> cmp,
-                             String symbol) {
+        NumberMatcher(Number expected, Function<Integer, Boolean> cmp, String symbol) {
             this.expected = expected;
             this.cmp = cmp;
             this.symbol = symbol;
diff --git a/hugegraph-common/src/main/java/org/apache/hugegraph/util/VersionUtil.java b/hugegraph-common/src/main/java/org/apache/hugegraph/util/VersionUtil.java
index cc98fa1c..8d633f02 100644
--- a/hugegraph-common/src/main/java/org/apache/hugegraph/util/VersionUtil.java
+++ b/hugegraph-common/src/main/java/org/apache/hugegraph/util/VersionUtil.java
@@ -82,8 +82,8 @@ public static String getImplementationVersion(Class<?> clazz) {
         String className = clazz.getSimpleName() + ".class";
         String classPath = Objects.requireNonNull(clazz.getResource(className)).toString();
         if (!classPath.startsWith("jar:file:")) {
-          // Class not from JAR
-          return null;
+            // Class not from JAR
+            return null;
         }
         int offset = classPath.lastIndexOf("!");
         assert offset > 0;
diff --git a/hugegraph-rpc/src/main/java/org/apache/hugegraph/config/RpcOptions.java b/hugegraph-rpc/src/main/java/org/apache/hugegraph/config/RpcOptions.java
index 782643ea..e4c9730f 100644
--- a/hugegraph-rpc/src/main/java/org/apache/hugegraph/config/RpcOptions.java
+++ b/hugegraph-rpc/src/main/java/org/apache/hugegraph/config/RpcOptions.java
@@ -19,9 +19,6 @@
 
 package org.apache.hugegraph.config;
 
-import org.apache.hugegraph.config.ConfigOption;
-import org.apache.hugegraph.config.OptionHolder;
-
 import static org.apache.hugegraph.config.OptionChecker.allowValues;
 import static org.apache.hugegraph.config.OptionChecker.disallowEmpty;
 import static org.apache.hugegraph.config.OptionChecker.rangeInt;
@@ -128,7 +125,7 @@ public static synchronized RpcOptions instance() {
                     "rpc.client_load_balancer",
                     "The rpc client uses a load-balancing algorithm to " +
                     "access multiple rpc servers in one cluster. Default " +
-                    "value is 'consistentHash', means forwording by request " +
+                    "value is 'consistentHash', means forwarding by request " +
                     "parameters.",
                     allowValues("random", "localPref", "roundRobin",
                                 "consistentHash", "weightRoundRobin"),
diff --git a/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcClientProvider.java b/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcClientProvider.java
index b17191a6..826c013a 100644
--- a/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcClientProvider.java
+++ b/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcClientProvider.java
@@ -41,6 +41,7 @@ public RpcClientProvider(HugeConfig config) {
         this.consumerConfig = StringUtils.isNotBlank(rpcUrl) ?
                               new RpcConsumerConfig(config, rpcUrl) : null;
     }
+
     public boolean enabled() {
         return this.consumerConfig != null;
     }
diff --git a/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcConsumerConfig.java b/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcConsumerConfig.java
index f2c9b920..796f8fbe 100644
--- a/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcConsumerConfig.java
+++ b/hugegraph-rpc/src/main/java/org/apache/hugegraph/rpc/RpcConsumerConfig.java
@@ -53,8 +53,8 @@ public class RpcConsumerConfig implements RpcServiceConfig4Client {
     private final List<ConsumerBootstrap<?>> bootstraps;
 
     static {
-         ExtensionLoaderFactory.getExtensionLoader(Cluster.class)
-                               .loadExtension(FanoutCluster.class);
+        ExtensionLoaderFactory.getExtensionLoader(Cluster.class)
+                              .loadExtension(FanoutCluster.class);
     }
 
     public RpcConsumerConfig(HugeConfig config, String remoteUrls) {
@@ -148,7 +148,7 @@ private static class FanoutCluster extends AbstractCluster {
 
         private static final Logger LOG = Log.logger(FanoutCluster.class);
 
-        public FanoutCluster(ConsumerBootstrap<?> consumerBootstrap) {
+        FanoutCluster(ConsumerBootstrap<?> consumerBootstrap) {
             super(consumerBootstrap);
         }
 
diff --git a/pom.xml b/pom.xml
index b10167e0..ad7e3a4c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -92,7 +92,6 @@
         <plugins>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.1</version>
                 <configuration>
                     <source>${compiler.source}</source>
                     <target>${compiler.target}</target>
@@ -136,7 +135,6 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
-                <version>2.6</version>
                 <configuration>
                     <archive>
                         <index>true</index>
@@ -222,7 +220,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>flatten-maven-plugin</artifactId>
-                <version>1.2.7</version>
+                <version>1.3.0</version>
                 <configuration>
                     <updatePomFile>true</updatePomFile>
                     <flattenMode>resolveCiFriendliesOnly</flattenMode>
@@ -255,7 +253,6 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-source-plugin</artifactId>
-                        <version>2.2.1</version>
                         <executions>
                             <execution>
                                 <id>attach-sources</id>
@@ -268,7 +265,6 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-javadoc-plugin</artifactId>
-                        <version>2.10.1</version>
                         <executions>
                             <execution>
                                 <id>attach-javadocs</id>
@@ -286,7 +282,6 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-gpg-plugin</artifactId>
-                        <version>1.5</version>
                         <executions>
                             <execution>
                                 <id>sign-artifacts</id>