diff --git a/backend.ai-client-tester/build.gradle b/backend.ai-client-tester/build.gradle
index c9d7699..e5e74df 100644
--- a/backend.ai-client-tester/build.gradle
+++ b/backend.ai-client-tester/build.gradle
@@ -4,18 +4,21 @@ apply plugin: 'application'
 mainClassName = "ai.backend.clienttester.Main"
 
 dependencies {
-    compile project(':backend.ai-client')
-    compile group: 'commons-cli', name: 'commons-cli', version:'1.3.1'
-    compile 'commons-io:commons-io:2.6'
+    implementation project(':backend.ai-client')
+    implementation group: 'commons-cli', name: 'commons-cli', version:'1.3.1'
+    implementation 'commons-io:commons-io:2.6'
+    implementation 'com.google.code.gson:gson:2.8.9'
 }
+
 jar {
     manifest {
         attributes  'Title': 'Backend.AI client lib tester', 'Version': version, 'Main-Class':'ai.backend.clienttester.Main'
     }
-    dependsOn configurations.runtime
+    dependsOn configurations.runtimeClasspath
     from {
-        configurations.compile.collect {it.isDirectory()? it: zipTree(it)}
+        configurations.runtimeClasspath.collect {it.isDirectory()? it: zipTree(it)}
     }
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
 run {
     if (project.hasProperty("appArgs")) {
diff --git a/backend.ai-client/build.gradle b/backend.ai-client/build.gradle
index 3e3c8a0..76f9a54 100644
--- a/backend.ai-client/build.gradle
+++ b/backend.ai-client/build.gradle
@@ -3,7 +3,6 @@ plugins {
     id 'java-library-distribution'
 }
 
-
 jar {
     manifest {
         attributes 'Title': 'Backend.AI Client for Java',
@@ -11,17 +10,18 @@ jar {
                    'Implementation-Version': version,
                    'Main-Class': 'ai.backend.client.Main'
     }
-    dependsOn configurations.runtime
+    dependsOn configurations.runtimeClasspath
     from {
-        configurations.compile.collect {it.isDirectory()? it: zipTree(it)}
+        configurations.runtimeClasspath.collect {it.isDirectory()? it: zipTree(it)}
     }
 }
 
 description = 'Backend.AI Client Library for Java'
 
+
 dependencies {
-    compile 'com.google.code.gson:gson:2.8.2'
-    compile 'com.squareup.okhttp3:okhttp:3.9.1'
-    testCompile 'org.junit.jupiter:junit-jupiter-api:5.0.1'
-    testCompile 'junit:junit:4.12'
+    implementation 'com.google.code.gson:gson:2.8.9'
+    implementation 'com.squareup.okhttp3:okhttp:3.9.1'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.0.1'
+    testImplementation 'junit:junit:4.12'
 }
diff --git a/build.gradle b/build.gradle
index 3774c3b..4f914b5 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,17 +1,18 @@
 allprojects  {
-  apply plugin: 'maven'
+  apply plugin: 'maven-publish'
   group = 'ai.backend.client'
   version = '0.3'
 }
 
 subprojects {
   apply plugin: 'java'
-  sourceCompatibility = 1.6
-  targetCompatibility = 1.6
+  sourceCompatibility = 1.7
+  targetCompatibility = 1.7
 
   repositories {
     mavenLocal()
-    
-    maven { url "http://repo.maven.apache.org/maven2" }
+    mavenCentral()
+
+    maven { url "https://repo.maven.apache.org/maven2" }
   }
 }
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 3b62185..f5b8a8d 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.2.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.3-all.zip
diff --git a/settings.gradle b/settings.gradle
index 75a11ef..060f391 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,6 +1,5 @@
 rootProject.name = 'BackendAI-Java-SDK'
-include ':backend.ai-client'
-include ':backend.ai-client-tester'
+include 'backend.ai-client',  'backend.ai-client-tester'
 
 project(':backend.ai-client').projectDir = "$rootDir/backend.ai-client" as File
 project(':backend.ai-client-tester').projectDir = "$rootDir/backend.ai-client-tester" as File