fixed java 8 test cases

Author: tanya732

lib/build.gradle

@@ -134,15 +134,23 @@ compileTestJava {
     options.compilerArgs = ["-Xlint:deprecation"]
 }
 
-//def testJava8 = tasks.register('testJava8', Test) {
-//    description = 'Runs unit tests on Java 8.'
-//    group = 'verification'
-//
-//    javaLauncher.set(javaToolchains.launcherFor {
-//        languageVersion = JavaLanguageVersion.of(8)
-//    })
-//    shouldRunAfter(tasks.named('test'))
-//}
+def testJava8 = tasks.register('testJava8', Test) {
+    description = 'Runs unit tests on Java 8.'
+    group = 'verification'
+
+    javaLauncher.set(javaToolchains.launcherFor {
+        languageVersion = JavaLanguageVersion.of(8)
+    })
+    shouldRunAfter(tasks.named('test'))
+
+    doFirst {
+        tasks.compileJava.options.release.set(8)
+    }
+
+    doLast {
+        tasks.compileJava.options.release.set(11)
+    }
+}
 
 def testJava17 = tasks.register('testJava17', Test) {
     description = 'Runs unit tests on Java 17.'