if (constructed == null || constructed.getTagClass() != BERTags.APPLICATION
                    || !(constructed.getBaseObject() instanceof ASN1Sequence)) {
                throw new IOException("Malformed SPNEGO token " + constructed);
            }

            final ASN1Sequence vec = (ASN1Sequence) constructed.getBaseObject();

            final ASN1ObjectIdentifier spnego = (ASN1ObjectIdentifier) vec.getObjectAt(0);

            assertEquals(0, top.getTagNo(), "Top-level tag number should be 0");
            assertTrue(top.getBaseObject() instanceof ASN1Sequence, "Base object should be a sequence");
            ASN1Sequence seq = (ASN1Sequence) top.getBaseObject();
            assertEquals(2, seq.size(), "Sequence should contain OID and [0] NegTokenInit");

            throw new PACDecodingException("Malformed kerberos ticket", e);
        }

        ASN1Sequence sequence;
        try {
            sequence = ASN1Util.as(ASN1Sequence.class, derToken.getBaseObject());
        } catch (IOException e) {
            throw new PACDecodingException("Malformed kerberos ticket", e);
        }

        Enumeration<?> fields = sequence.getObjects();