When an enum is nested in several messages, a ClassNotFoundException is thrown when calling the DataFileWriter append method. I've attached a stack trace.
The offending line (ProtobufData.java 112):
Class c = Class.forName(SpecificData.getClassName(s));
Say we have an enum nested as follows (I've left out some syntax):
Expected class name: org.foo.bar.A$B$C$D
Actual class name being returned: org.foo.bar.A$D
Only the package name, outer class, and enum class name are being taken into consideration. All parent classes besides the outer class are ignored. Nested messages are not afflicted by the same problem because they are resolved recursively.
Please let me know if you require any more information or if anything is unclear.