Why is the class version missing

    public byte[] transform(byte[] arg0, int arg1, int arg2) {        ClassReader cr = null;        ClassWriter cw = null;        cr = new ClassReader(arg0);        cw = new ClassWriter(cr, ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);        //cr.accept(cw,ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS );        return cw.toByteArray();    }