Serializing java.lang.Thread fails on JDK 11 and above (should suppress serialization of ClassLoader)

[cowtowncoder]

Looks like serialization of Thread (for exp, Thread.currentThread()) fails with StackOverflow on JDK11, due to addition of a new property. Looks like this might be via ClassLoader, which probably should not really be serialized anyway.
Passed on JDK 8.

[cowtowncoder]

Since this does change output, will not try to resolve in 2.12, will target 2.13.

Work-around for anyone hit by this would be to add ClassLoader type into "ignored types" list, like so:

    mapper.configOverride(ClassLoader.class).setIsIgnoredType(true);

which I think should work. If not, mix-in with @JsonIgnoredType against ClassLoader definitely should work.