DoesNotWork.java

public class DoesNotWork {
  public static void main(String[] args) {
    // this will compile once, fail on execution, and subsequent compiles fail
    Messages.Status me = Messages.Status.newBuilder().buildPartial();
    System.out.println("It Works!");
  }
}

messages.proto

enum STATUS {
  OK = 1;
}

message Status {
  required STATUS code = 1;
}

message Person {
  required string name = 1;
}

run.sh

#!/bin/bash
echo "protobuf + java = 💩"

echo "-----java info-----"
java -version

echo "-----protobuf info-----"
protoc --version

printf "\n\n"

read -rsp $'Press any key to download protobuf jar...\n' -n1 key
wget http://central.maven.org/maven2/com/google/protobuf/protobuf-java/2.6.1/protobuf-java-2.6.1.jar
read -rsp $'Press any key to compile messages.proto...\n' -n1 key
protoc --proto_path . --java_out . messages.proto
read -rsp $'Press any key to compile the working example...\n' -n1 key
javac Works.java -cp protobuf-java-2.6.1.jar:.
read -rsp $'Press any key to run the working example...\n' -n1 key
java -cp protobuf-java-2.6.1.jar:. Works
read -rsp $'Press any key to clear compiled classes...\n' -n1 key
rm *.class
read -rsp $'Press any key to compile the non-working example...\n' -n1 key
javac DoesNotWork.java -cp protobuf-java-2.6.1.jar:.
read -rsp $'Press any key to run the non-working example...\n' -n1 key
java -cp protobuf-java-2.6.1.jar:. DoesNotWork
read -rsp $'Press any key to compile the non-working example...\n' -n1 key
javac DoesNotWork.java -cp protobuf-java-2.6.1.jar:.

echo "Clean up files with $ rm Messages.java *.class protobuf-java-2.6.1.jar"

Works.java

public class Works {
  public static void main(String[] args) {
    // this will work all day every day
    Messages.Person me = Messages.Person.newBuilder().buildPartial();
    System.out.println("It Works!");
  }
}

This demonstrates a failure on OSX Oracle JVM 1.8:

Exception in thread "main" java.lang.NoClassDefFoundError: Messages$STATUS (wrong name: Messages$Status)