Resolve #75 by adding DynamicClassLoader

src/main/java/org/update4j/ConfigImpl.java

@@ -457,9 +457,18 @@ static void doLaunch(Configuration config, Injectable injectable, Launcher launc
 		java.lang.module.Configuration cf = parent.configuration()
 						.resolveAndBind(ModuleFinder.of(), finder, moduleNames);
 
-		ClassLoader parentClassLoader = Thread.currentThread().getContextClassLoader();
-		ClassLoader classpathLoader = new URLClassLoader("classpath", classpaths.toArray(new URL[classpaths.size()]),
-						parentClassLoader);
+
+		ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+		ClassLoader classpathLoader = DynamicClassLoader.findAncestor(contextClassLoader);
+		if(classpathLoader != null) {
+			DynamicClassLoader dynamic = (DynamicClassLoader) classpathLoader;
+			for(URL url : classpaths) {
+				dynamic.add(url);
+			}
+		} else {
+			classpathLoader = new URLClassLoader("classpath", classpaths.toArray(new URL[classpaths.size()]),
+						contextClassLoader);
+		}
 
 		ModuleLayer.Controller controller = ModuleLayer.defineModulesWithOneLoader(cf, List.of(parent),
 						classpathLoader);
@@ -502,7 +511,7 @@ static void doLaunch(Configuration config, Injectable injectable, Launcher launc
 			}
 		}
 
-		ClassLoader contextClassLoader = classpathLoader;
+		contextClassLoader = classpathLoader;
 		if (moduleNames.size() > 0) {
 			contextClassLoader = layer.findLoader(moduleNames.get(0));
 		}

src/main/java/org/update4j/DynamicClassLoader.java

@@ -0,0 +1,56 @@
+package org.update4j;
+
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Paths;
+
+public final class DynamicClassLoader extends URLClassLoader {
+
+	static {
+		registerAsParallelCapable();
+	}
+
+	public DynamicClassLoader(String name, ClassLoader parent) {
+		super(name, new URL[0], parent);
+	}
+
+	/*
+	 * Required when this classloader is used as the system classloader
+	 */
+	public DynamicClassLoader(ClassLoader parent) {
+		this("classpath", parent);
+	}
+
+	public DynamicClassLoader() {
+		this(Thread.currentThread().getContextClassLoader());
+	}
+
+	void add(URL url) {
+		addURL(url);
+	}
+
+	public static DynamicClassLoader findAncestor(ClassLoader cl) {
+		do {
+
+			if(cl instanceof DynamicClassLoader)
+				return (DynamicClassLoader) cl;
+
+			cl = cl.getParent();
+		} while(cl != null);
+
+		return null;
+	}
+
+	/*
+	 *  Required for Java Agents when this classloader is used as the system classloader
+	 */
+	@SuppressWarnings("unused")
+	private void appendToClassPathForInstrumentation(String jarfile) {
+		try {
+			add(Paths.get(jarfile).toRealPath().toUri().toURL());
+		} catch (IOException e) {
+			new AssertionError(e);
+		}
+	}
+}

src/main/java/org/update4j/service/DefaultLauncher.java

@@ -96,12 +96,12 @@ public void run(LaunchContext context) {
 		System.setProperty("update4j.suppress.warning.access", "true");
 
 		try {
-			Class<?> clazz = Class.forName(mainClass, true, context.getClassLoader());
+			Class<?> clazz = context.getClassLoader().loadClass(mainClass);
 
 			// first check for JavaFx start method
 			Class<?> javafx = null;
 			try {
-				javafx = Class.forName("javafx.application.Application", true, context.getClassLoader());
+				javafx = context.getClassLoader().loadClass("javafx.application.Application");
 			} catch (ClassNotFoundException e) {
 				// no JavaFx present, skip.
 			}