David Yu

It looks like ```Thread.currentThread().getContextClassLoader()``` returned null based on your stacktrace.

What jvm version are you using?

Try a newer version of java 1.8 That release you have may have had a regression (bug)

@Mr14huashao Will have to investigate. PRs are definitely welcome.

You should **not** directly call that. Remember that the classes passed to that function must be user-defined pojos and not jdk core classes.

Easiest solution: ```java public abstract class Item { ``` If you can't make it abstract, then: ``` -Dprotostuff.runtime.morph_non_final_pojos=true ``` or ```java static final DefaultIdStrategy STRATEGY = new DefaultIdStrategy(IdStrategy.DEFAULT_FLAGS | IdStrategy.MORPH_NON_FINAL_POJOS);...