[DISCUSS] Lots of test failures on JDK11

[Wei-Chiu Chuang <we...@apache.org>]

I see lots of tests that fail consistently on JDK11.
https://ci-hadoop.apache.org/job/hadoop-qbt-trunk-java11-linux-x86_64/160/testReport/

A number of them are YARN tests. I am preparing the 3.3.1 release and in
the current state I am not confident in the quality of this release. Please
help out!

Some failed for

Caused by: java.lang.IllegalAccessError: class
jdk.internal.reflect.ConstructorAccessorImpl loaded by
org.powermock.core.classloader.MockClassLoader @1a3869f4 cannot access
jdk/internal/reflect superclass jdk.internal.reflect.MagicAccessorImpl


Some failed for

java.lang.ClassCastException: class
org.apache.hadoop.yarn.client.TestRMFailoverProxyProvider$TestProxy
cannot be cast to class org.apache.hadoop.yarn.client.RMProxy
(org.apache.hadoop.yarn.client.TestRMFailoverProxyProvider$TestProxy
and org.apache.hadoop.yarn.client.RMProxy are in unnamed module of
loader 'app')