cglib: IllegalArgumentException in BridgeMethodResolver using JDK 9

Hi team,

We’re trying to upgrade the Gradle build to make it run on JDK 9, and we’re facing issues with our tests that use mocking. Some of them are failing with the following exception:

Caused by: java.lang.IllegalArgumentException
	at net.sf.cglib.proxy.BridgeMethodResolver.resolveAll(BridgeMethodResolver.java:63)
	at net.sf.cglib.proxy.Enhancer.emitMethods(Enhancer.java:1132)
	at net.sf.cglib.proxy.Enhancer.generateClass(Enhancer.java:630)
	at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
	at net.sf.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:329)
	at net.sf.cglib.proxy.Enhancer.generate(Enhancer.java:492)
	at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:93)
	at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:91)
	at net.sf.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
	at java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at net.sf.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
	at net.sf.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
	at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:116)
	at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291)
	at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:480)
	at net.sf.cglib.proxy.Enhancer.createClass(Enhancer.java:337)
	at org.spockframework.mock.runtime.ProxyBasedMockFactory$CglibMockFactory.createMock(ProxyBasedMockFactory.java:91)
	at org.spockframework.mock.runtime.ProxyBasedMockFactory.create(ProxyBasedMockFactory.java:49)
	at org.spockframework.mock.runtime.JavaMockFactory.create(JavaMockFactory.java:51)
	at org.spockframework.mock.runtime.CompositeMockFactory.create(CompositeMockFactory.java:44)
	at org.spockframework.lang.SpecInternals.createMock(SpecInternals.java:45)
	at org.spockframework.lang.SpecInternals.createMockImpl(SpecInternals.java:281)
	at org.spockframework.lang.SpecInternals.MockImpl(SpecInternals.java:83)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at ReproSpec.should not throw IllegalArgumentException(ReproSpec.groovy:6)

The reproduction instructions can be found in this repository: https://github.com/melix/repro-cglib-bug-jdk9

Let me know if I can help.