Any attempt to call ObjectStreamClass.lookup() on an interface that
extends Serializable (but not Externalizable) will result in a
NullPointerException on recent builds of merlin:

$ cat Foo.java

import java.io.*;

interface Bar extends Serializable {}

public class Foo {
    public static void main(String[] args) {
        ObjectStreamClass.lookup(Bar.class);
    }
}

$ javac Foo.java
$ java Foo
Exception in thread "main" java.lang.NullPointerException
        at java.lang.Class.isAssignableFrom(Native Method)
        at sun.misc.ClassReflector.getSerializableConstructor(ClassReflector.java:1181)
        at sun.misc.ClassReflector.getInvocables(ClassReflector.java:1143)
        at sun.misc.ClassReflector.access$900(ClassReflector.java:27)
        at sun.misc.ClassReflector$2.run(ClassReflector.java:1058)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.misc.ClassReflector.createClassReflector(ClassReflector.java:1055)
        at sun.misc.ClassReflector.getClassReflector(ClassReflector.java:1043)
        at sun.misc.ClassReflector.access$100(ClassReflector.java:27)
        at sun.misc.ClassReflector$Factory.getClassReflector(ClassReflector.java:87)
        at java.io.ObjectStreamClass.<init>(ObjectStreamClass.java:237)
        at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:226)
        at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:103)
        at Foo.main(Foo.java:7)