using TL from around b28 (early November 2003)

abstract class ByteBuffer implements Comparable<ByteBuffer> {
    public int compareTo(Object o) {
        return 1;
    }
}

results in

java.lang.NullPointerException
        at com.sun.tools.javac.comp.TransTypes.addBridgeIfNeeded(TransTypes.java:256)
        at com.sun.tools.javac.comp.TransTypes.addBridges(TransTypes.java:292)
        at com.sun.tools.javac.comp.TransTypes.addBridges(TransTypes.java:311)
        at com.sun.tools.javac.comp.TransTypes.translateClass(TransTypes.java:676)
        at com.sun.tools.javac.comp.TransTypes.visitClassDef(TransTypes.java:351)
        at com.sun.tools.javac.tree.Tree$ClassDef.accept(Tree.java:429)
        at com.sun.tools.javac.comp.TransTypes.translate(TransTypes.java:329)
        at com.sun.tools.javac.comp.TransTypes.translateTopLevelClass(TransTypes.java:693)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:439)
        at com.sun.tools.javac.main.Main.compile(Main.java:598)
        at com.sun.tools.javac.main.Main.compile(Main.java:546)
        at com.sun.tools.javac.Main.compile(Main.java:41)
        at com.sun.tools.javac.Main.main(Main.java:32)