diff --git a/lib/java/build.gradle b/lib/java/build.gradle
index 726d7b7..3e750fd 100644
--- a/lib/java/build.gradle
+++ b/lib/java/build.gradle
@@ -39,7 +39,7 @@
     id 'java-library'
     id 'maven'
     id 'signing'
-    id 'com.github.johnrengelman.shadow' version '4.0.4'
+    id 'com.github.johnrengelman.shadow' version '6.1.0'
     id "com.github.spotbugs" version "4.7.1"
     id "com.diffplug.spotless" version "6.4.2"
 }
diff --git a/lib/java/gradle/environment.gradle b/lib/java/gradle/environment.gradle
index 2f49a0d..224f10f 100644
--- a/lib/java/gradle/environment.gradle
+++ b/lib/java/gradle/environment.gradle
@@ -64,14 +64,14 @@
 }
 
 dependencies {
-    compile "org.slf4j:slf4j-api:${slf4jVersion}"
-    compile "org.apache.httpcomponents:httpclient:${httpclientVersion}"
-    compile "org.apache.httpcomponents:httpcore:${httpcoreVersion}"
-    compile "javax.servlet:javax.servlet-api:${servletVersion}"
-    compile "javax.annotation:javax.annotation-api:${javaxAnnotationVersion}"
-    compile "org.apache.commons:commons-lang3:3.12.0"
+    implementation "org.slf4j:slf4j-api:${slf4jVersion}"
+    implementation "org.apache.httpcomponents:httpclient:${httpclientVersion}"
+    implementation "org.apache.httpcomponents:httpcore:${httpcoreVersion}"
+    implementation "javax.servlet:javax.servlet-api:${servletVersion}"
+    implementation "javax.annotation:javax.annotation-api:${javaxAnnotationVersion}"
+    implementation "org.apache.commons:commons-lang3:3.12.0"
 
     testImplementation "org.junit.jupiter:junit-jupiter:${junitVersion}"
-    testCompile "org.mockito:mockito-all:${mockitoVersion}"
-    testRuntime "org.slf4j:slf4j-log4j12:${slf4jVersion}"
+    testImplementation "org.mockito:mockito-all:${mockitoVersion}"
+    testRuntimeOnly "org.slf4j:slf4j-log4j12:${slf4jVersion}"
 }
diff --git a/lib/java/gradle/functionalTests.gradle b/lib/java/gradle/functionalTests.gradle
index 15737f5..e8a3e89 100644
--- a/lib/java/gradle/functionalTests.gradle
+++ b/lib/java/gradle/functionalTests.gradle
@@ -34,15 +34,27 @@
     }
 }
 
+// see https://docs.gradle.org/current/userguide/java_library_plugin.html
+// 1. defines cross test implementation that includes all test implementation, which in turn
+//    contains all implementation dependencies
+// 2. defines cross test runtime that further includes test runtime only dependencies
+// 3. the cross test implementation will need to depends on main and test output
+// 4. shadow jar will package both main and test source set, along with cross test runtime dependencies
 configurations {
-    crossTestCompile { extendsFrom testCompile }
-    crossTestRuntime { extendsFrom crossTestCompile, testRuntime }
+    crossTestImplementation {
+        description "implementation for cross test"
+        extendsFrom testImplementation
+    }
+    crossTestRuntime {
+        description "runtime dependencies for cross test"
+        extendsFrom crossTestImplementation, testRuntimeOnly
+    }
 }
 
 dependencies {
-    crossTestCompile "org.apache.tomcat.embed:tomcat-embed-core:${tomcatEmbedVersion}"
-    crossTestCompile sourceSets.main.output
-    crossTestCompile sourceSets.test.output
+    crossTestImplementation "org.apache.tomcat.embed:tomcat-embed-core:${tomcatEmbedVersion}"
+    crossTestImplementation sourceSets.main.output
+    crossTestImplementation sourceSets.test.output
 }
 
 // I am using shadow plugin to make a self contained functional test Uber JAR that
@@ -53,19 +65,17 @@
     description = 'Assemble a test JAR file for cross-check execution'
     // make sure the runners are created when this runs
     dependsOn 'generateRunnerScriptForClient', 'generateRunnerScriptForServer', 'generateRunnerScriptForNonblockingServer', 'generateRunnerScriptForTServletServer'
-
-    baseName = 'functionalTest'
-    destinationDir = file("$buildDir/functionalTestJar")
-    classifier = null
-
+    archiveBaseName.set('functionalTest')
+    destinationDirectory = file("$buildDir/functionalTestJar")
+    archiveClassifier.set(null)
     // We do not need a version number for this internal jar
-    version = null
-
+    archiveVersion.set(null)
     // Bundle the complete set of unit test classes including generated code
     // and the runtime dependencies in one JAR to expedite execution.
+    // see https://imperceptiblethoughts.com/shadow/custom-tasks/
     from sourceSets.test.output
     from sourceSets.crossTest.output
-    configurations = [project.configurations.testRuntime]
+    configurations = [project.configurations.crossTestRuntime]
 }
 
 // Common script runner configuration elements