クラスローダの問題？

最初はMavenの依存ライブラリにGroovyとJRubyを入れてみたが、案の定asmがコンフリクトしました。そこで、ClassLoaderを指定するScriptEngineManagerを使い、スクリプト関連のライブラリはローカルフォルダから個別のクラスローダでロードする形にしました。
これでうまくいく・・・と思いきや、テストが失敗。JRuby自体は認識しているのですが、org.jruby.javasupport.JavaがClassNotFoundになってしまうのです・・・。
JRubyのjarを直接クラスパスに追加するならば、問題なくテストは成功します（Groovyはこけるけど）。なのでClassLoader絡みなんだとは思うのですが。

追記

URLClassLoader classLoader = new URLClassLoader(urls);
classLoader.loadClass("org.jruby.javasupport.Java");

とすれば、ちゃんとロードされやがります。これは、ScriptEngineManager側のバグ？

java.lang.ClassNotFoundException: org.jruby.javasupport.Java
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
	at org.jruby.ext.LateLoadingLibrary.load(LateLoadingLibrary.java:53)
	at org.jruby.runtime.load.LoadService.tryLoadingLibraryOrScript(LoadService.java:564)
	at org.jruby.runtime.load.LoadService.smartLoad(LoadService.java:275)
	at org.jruby.runtime.load.LoadService.require(LoadService.java:282)
	at com.sun.script.jruby.JRubyScriptEngine.init(JRubyScriptEngine.java:516)
	at com.sun.script.jruby.JRubyScriptEngine.<init>(JRubyScriptEngine.java:102)
	at com.sun.script.jruby.JRubyScriptEngine.<init>(JRubyScriptEngine.java:98)
	at com.sun.script.jruby.JRubyScriptEngineFactory.getScriptEngine(JRubyScriptEngineFactory.java:134)
	at javax.script.ScriptEngineManager.getEngineByName(ScriptEngineManager.java:243)
	at jp.deathmarch.pilika.expression.FunctionEngine.getInvocable(FunctionEngine.java:84)
	at jp.deathmarch.pilika.expression.FunctionEngine.eval(FunctionEngine.java:54)
	at jp.deathmarch.pilika.expression.ExpressionEngine.getValue(ExpressionEngine.java:120)
	at jp.deathmarch.pilika.expression.ExpressionEngine.getValue(ExpressionEngine.java:93)
	at jp.deathmarch.pilika.expression.ExpressionEngine.eval(ExpressionEngine.java:78)
	at jp.deathmarch.pilika.template.ExpressionNode.getText(ExpressionNode.java:44)
	at jp.deathmarch.pilika.template.BindTemplate.render(BindTemplate.java:37)
	at jp.deathmarch.pilika.RenderTest_script.render_PlkDefRuby_format(RenderTest_script.java:45)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
	at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
	at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:62)
	at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:140)
	at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:127)
	at org.apache.maven.surefire.Surefire.run(Surefire.java:177)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:616)
	at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:345)
	at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:1009)