Java 11 Migration Guide: Release Cycle, LTS, Tool Updates, JPMS Migration, and Compatibility Issues

Background

Discusses the new JDK release cycle, OpenJDK feature standardization, and long‑term support (LTS) versions.

New Release Cycle

Major releases occur every six months (March and September) with two minor updates following each major release.

OpenJDK as the Standard JDK

Since September 2018 OpenJDK and Oracle JDK are functionally identical; OpenJDK 11 is maintained by the Red Hat community, providing reliable production support.

LTS Versions

Commercial JDK vendors define LTS at versions 11, 17, 23, etc. OpenJDK guarantees at least four years of maintenance for these releases, with binaries available from AdoptOpenJDK.

Amazon Corretto

Amazon offers its own OpenJDK distribution (Corretto) under GPL+CE, adding security, performance, and stability fixes, supporting Linux, macOS, and Windows, with LTS for Java 8 until 2023 and Java 11 until 2024, and quarterly updates.

Preparing Migration

1. Update Development and Build Tools

IntelliJ IDEA 2018.2

Eclipse Photon 4.9RC2 with Java 11 plugin

Maven 3.5.0

Maven compiler plugin 3.8.0

Surefire and failsafe 2.22.0

Gradle 5.0

Replace discontinued tools: FindBugs → SpotBugs, Cobertura → JaCoCo.

Upgrade bytecode‑related libraries (ASM 7.0, Byte Buddy 1.9.0, cglib 3.2.8, Javassist 3.23.1‑GA) and frameworks (Spring ≥5.1, Mockito ≥2.20.0).

2. JPMS Migration

2.1 Java EE modules removed

Compilation fails when using removed packages, e.g.:

error: package javax.xml.bind does not exist
import javax.xml.bind.JAXBException;

Runtime error example:

Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
    at monitor.Main.main(Main.java:27)

Required Maven dependencies:

<dependency>
    <groupId>com.sun.activation</groupId>
    <artifactId>javax.activation</artifactId>
    <version>1.2.0</version>
</dependency>

<dependency>
    <groupId>javax.transaction</groupId>
    <artifactId>javax.transaction-api</artifactId>
    <version>1.2</version>
</dependency>

<dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.2.8</version>
</dependency>
... (additional JAXB and JAX‑WS dependencies) ...

2.2 Module visibility and internal API access

Use --add-exports to export non‑public packages and --add-opens to open them for deep reflection. Example:

javac --add-exports java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED

Run with:

java --add-exports java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED \
     --add-opens java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED

Control illegal‑access warnings with --illegal-access=permit|warn|debug|deny .

2.3 Detecting internal APIs with jdeps

jdeps --jdk-internals -R --class-path 'libs/*' $project

Sample output shows replacements such as sun.misc.BASE64Encoder → java.util.Base64 and sun.reflect.Reflection → java.lang.StackWalker .

2.4 ClassLoader changes

JDK 8 uses bootstrap, extension, and application classloaders; JDK 9+ replaces the extension loader with a platform loader and the application loader is no longer a URLClassLoader . Dynamic loading must use a custom java.security.SecureClassLoader instead of casting to URLClassLoader .

String pathSeparator = System.getProperty("path.separator");
String[] classPathEntries = System.getProperty("java.class.path").split(pathSeparator);

2.5 Obsolete JVM options

Options are categorized as Obsolete (accepted but ignored), Deprecated (accepted with warning), and Removed (causes error). References to official Java documentation are provided.

Framework Compatibility Issues

OpenJDK 11 incompatibility with Spring Cloud Finchley (see linked article).

Lombok compilation errors – upgrade to Lombok 1.18.+.

Spring Cloud Hystrix ThreadPool bug.