java.lang.NoClassDefFoundError: java/applet/Applet on modern JDKs (Java 26+) due to legacy Applet references #281

Description

When running UI automation tests built on top of AssertJ Swing under modern JDK environments, specifically JDK 26 or newer, the test suite crashes during initialization with a java.lang.NoClassDefFoundError targeting java/applet/Applet.

The Applet API has been completely removed from the standard JDK classpath in Java 26 under [JEP 504: Remove the Applet API].
Since AssertJ Swing still carries legacy references, internal fixtures, or utilities inherited from the original FEST Swing codebase that depend on java.applet.Applet, the framework fails immediately upon class loading.

Stack Trace

java.lang.NoClassDefFoundError: java/applet/Applet
	at io.github.kriolos.opos.automation.BasePosRobotIT.setUpBase(BasePosRobotIT.java:83)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1612)
Caused by: java.lang.ClassNotFoundException: java.applet.Applet
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:502)

Environment

• Java Version: JDK 26+ (JEP 504 compliant)
• OS: Agnostic
• Library: AssertJ Swing (Core automation engine)

Expected Behavior

AssertJ Swing should be executable on modern standard runtimes (JDK 26+) without requiring or resolving deprecated and now-deleted packages like java.applet.*.

Suggested Fix

1. Completely remove or refactor any code paths, modules, or internal test runners (such as legacy Applet viewers/fixtures) that reference java.applet.Applet or javax.swing.JApplet.
2. Fully decouple standard desktop JFrame components from any Applet-based class loading mechanisms to restore compatibility with current and future JDK ecosystems.