diff --git a/lib/java/build.gradle b/lib/java/build.gradle
index 9184f7b..57a8e1e 100644
--- a/lib/java/build.gradle
+++ b/lib/java/build.gradle
@@ -19,6 +19,11 @@
 
 // Using the legacy plugin classpath for Clover so it can be loaded optionally
 buildscript {
+    // strictly enforce the minimum version of Java required to build and fail fast
+    if (JavaVersion.current() < JavaVersion.VERSION_1_8) {
+        throw new GradleException("The java version used is ${JavaVersion.current()}, but must be at least ${JavaVersion.VERSION_1_8}")
+    }
+
     repositories {
         mavenCentral()
         google()
diff --git a/lib/java/gradle/sourceConfiguration.gradle b/lib/java/gradle/sourceConfiguration.gradle
index 07c2a7f..d15c117 100644
--- a/lib/java/gradle/sourceConfiguration.gradle
+++ b/lib/java/gradle/sourceConfiguration.gradle
@@ -46,6 +46,9 @@
 // ----------------------------------------------------------------------------
 // Compiler configuration details
 
+// These two properties are still needed on JDK8, and possibly used directly by
+// plugins. However, the '--release' option added below makes these two
+// properties redundant when building with JDK9 or later.
 sourceCompatibility = '1.8'
 targetCompatibility = '1.8'
 
@@ -53,6 +56,10 @@
     options.encoding = 'UTF-8'
     options.debug = true
     options.deprecation = true
+    // the following is to build with Java 8 specifications, even when building with JDK9 or later
+    if (JavaVersion.current() > JavaVersion.VERSION_1_8) {
+        options.compilerArgs.addAll(['--release', '8'])
+    }
     // options.compilerArgs.addAll('-Xlint:unchecked')
 }