Java 8 ClassFormatException for interface with static methods, but only when using assertions

I started getting ClassFormatExceptions that I couldn't explain related to interfaces with static methods. I trimmed it down to this test case:

public interface ModifierTest
{
    public static final int DELTA = 10;

    public static int increment(int value)
    {
        assert value > 0; // Problem line
        return value + DELTA;
    }
}

public class ModifierExec
{
    public static void main(String[] args)
    {
        System.out.println(ModifierTest.class);
    }
}

      

        
        
        
      

    

Without an assertion in the increment () method, everything is fine. But with the assertion, I am getting a runtime exception (compilation is fine):

Exception in thread "main" java.lang.ClassFormatError: Illegal field modifiers in class ModifierTest: 0x1018
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$100(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at com.c4.camgen.ModifierExec.main(ModifierExec.java:7)

      

        
        
        
      

    

It's easy to work with, but I'm curious if this is a bug in Java or the correct (if weird) behavior. I can't find any references to assertions affecting field modifiers.

Can anyone tell me what's going on? Running in Eclipse Kepler under jdk 1.8.0_20.