GitLab CI: replace JDK 16 with the latest LTS JDK 17.

Author: greenrobot-team

.gitlab-ci.yml

@@ -98,11 +98,12 @@ test-jdk-8:
   variables:
     TEST_JDK: 8
 
-test-jdk-16:
+# JDK 17 is the latest LTS release.
+test-jdk-17:
   extends: .test-asan-template
   needs: ["test-jdk-8"]
   variables:
-    TEST_JDK: 16
+    TEST_JDK: 17
 
 test-jdk-x86:
   extends: .test-template

tests/objectbox-java-test/build.gradle

@@ -65,7 +65,7 @@ test {
         println("Will run tests with $javaExecutablePath")
         executable = javaExecutablePath
     } else if (System.getenv("TEST_JDK") != null) {
-        // to run tests on a different JDK
+        // To run tests on a different JDK, uses Gradle toolchains API (https://docs.gradle.org/current/userguide/toolchains.html)
         def sdkVersionInt = System.getenv("TEST_JDK") as Integer
         println("Will run tests with JDK $sdkVersionInt")
         javaLauncher.set(javaToolchains.launcherFor {