RFR: 8222422: vmTestbase/nsk/jdi/ClassLoaderReference/definedClasses tests failed with Unexpected Exception: null

[Daniil Titov]

Please review the change that fixes an intermittent failure of the test.

The tests checks the implementation of  the com.sun.tools.jdi.ClassLoaderReference class. The problem here is that while com.sun.tools.jdi.ClassLoaderReferenceImpl.definedClasses() iterates over all loaded classes to retrieve a classloader and compares it to the current one, some of the classes might become unloaded and garbage collected (e.g. org.graalvm.compiler.nodes.InliningLog$$Lambda$41.899832640 or jdk.internal.reflect.GeneratedConstructorAccessor1, etc.). If this happens then the attempt to retrieve a classloader for the collected class results in com.sun.jdi.ObjectCollectedException being thrown.

The fix catches this com.sun.jdi.ObjectCollectedException and continues iterating over the rest of the classes.

Webrev: http://cr.openjdk.java.net/~dtitov/8222422/webrev.01
Bug: https://bugs.openjdk.java.net/browse/JDK-8222422 

Thanks!
--Daniil