Enums produce serialization failures whether they are by themselves or part of a POJO in the stream. I've tried running in IntelliJ IDEA and also via flink run. Here is a small program to reproduce:
I took a look at that line in EnumSerializer.java and swapped out the reflection on the "values" method for the simpler `enumClass.getEnumConstants()`, and that seems to work after I install my custom flink-core jar. I believe this is because http://docs.oracle.com/javase/tutorial/reflect/special/enumMembers.html specifically states you cannot reflect on the "values" method since it is implicitly generated at compile time.