Internal APIs stricter access on Java11 require unit tests and example change

[NingZhang-e]

Change javassist version to 3.24.0-GA which support Java11 and switch to JDK11 to build this project.
Many unit tests will fail, like DelegateProxyTest.createNewProxyClass():

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access using Lookup on javassist.util.proxy.DefineClassHelper (file:/C:/Opensource/javassist/target/classes/) to class java.util.ArrayList
WARNING: Please consider reporting this to the maintainers of javassist.util.proxy.DefineClassHelper
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
FAILED: createNewProxyClass
com.ericsson.commonlibrary.proxy.ProxyException: Not able to create proxy
	at com.ericsson.commonlibrary.proxy.InterceptableProxyFactory.build(InterceptableProxyFactory.java:92)
	at com.ericsson.commonlibrary.proxy.InterceptableProxyFactory.createANewClassProxy(InterceptableProxyFactory.java:317)
	at com.ericsson.commonlibrary.proxy.Proxy.delegateClass(Proxy.java:73)
	at com.ericsson.commonlibrary.proxy.Proxy.delegate(Proxy.java:69)
	at com.ericsson.commonlibrary.proxy.DelegateProxyTest.createNewProxyClass(DelegateProxyTest.java:213)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
	at org.testng.internal.Invoker.invokeMethod(Invoker.java:580)
	at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:716)
	at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:988)
	at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
	at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
	at org.testng.TestRunner.privateRun(TestRunner.java:648)
	at org.testng.TestRunner.run(TestRunner.java:505)
	at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
	at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
	at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
	at org.testng.SuiteRunner.run(SuiteRunner.java:364)
	at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
	at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
	at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208)
	at org.testng.TestNG.runSuitesLocally(TestNG.java:1137)
	at org.testng.TestNG.runSuites(TestNG.java:1049)
	at org.testng.TestNG.run(TestNG.java:1017)
	at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
	at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
	at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
Caused by: java.lang.RuntimeException: Class not in same package as lookup class: java.util.ArrayList has no permission to define the class
	at javassist.util.proxy.ProxyFactory.createClass3(ProxyFactory.java:614)
	at javassist.util.proxy.ProxyFactory.createClass2(ProxyFactory.java:587)
	at javassist.util.proxy.ProxyFactory.createClass1(ProxyFactory.java:523)
	at javassist.util.proxy.ProxyFactory.createClass(ProxyFactory.java:449)
	at javassist.util.proxy.ProxyFactory.create(ProxyFactory.java:789)
	at javassist.util.proxy.ProxyFactory.create(ProxyFactory.java:774)
	at com.ericsson.commonlibrary.proxy.InterceptableProxyFactory.createProxyObject(InterceptableProxyFactory.java:237)
	at com.ericsson.commonlibrary.proxy.InterceptableProxyFactory.build(InterceptableProxyFactory.java:90)
	... 29 more
Caused by: javassist.CannotCompileException: Class not in same package as lookup class: java.util.ArrayList has no permission to define the class
	at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:300)
	at javassist.util.proxy.DefineClassHelper$Java11.defineClass(DefineClassHelper.java:48)
	at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:263)
	at javassist.util.proxy.FactoryHelper.toClass(FactoryHelper.java:136)
	at javassist.util.proxy.ProxyFactory.createClass3(ProxyFactory.java:603)
	... 36 more

Because unit test is executed on ArrayList which is Java internal class, the error happened.
I created one unit test towards javassist directly:

public void testJava11() throws Exception {
    	ProxyFactory factory = new ProxyFactory();
        factory.setSuperclass(HashMap.class);
        
        HashMap e = (HashMap)factory.create(null, null, new MethodHandler() {
            @Override
            public Object invoke(Object self, Method thisMethod,
                    Method proceed, Object[] args) throws Throwable {
                return proceed.invoke(self, args);
            }
        });
    }

Same error will happen. If changing HashMap to one customized new class, there is no such issue.
Here is one article to describe the possible reason:
https://blog.codefx.org/java/java-11-migration-guide/#Illegal-Access-To-Internal-APIs

[NingZhang-e]

Post this issue on javassist page:

jboss-javassist/javassist#228

[NingZhang-e]

I just tried some workaround to bypass Java11 issue: create one temp class extend Java built-in class, then create proxy of this created temp class.
Something like below in InterceptableProxyFactory.java#L315

if ("java.util".equals(classToIntercept.getPackageName())) {
        ClassPool pool = ClassPool.getDefault();
        CtClass cc = pool.makeClass("com.ericsson.commonlibrary.proxy." + classToIntercept.getName());
        try {
	       cc.setSuperclass(pool.get(classToIntercept.getName()));
		builder.setSuperclass(cc.toClass());
	} catch (CannotCompileException | NotFoundException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}        	
} else {
        builder.setSuperclass(classToIntercept);
 }

It works well.
I will seek fix to all similar issues.

[NingZhang-e]

Someone else fixed the issue in their own project:
jboss-javassist/javassist#228 (comment)

[NingZhang-e]

There is already one fix for this issue. Then we could wait for new release of javassist, then update pom and deliver a new release.