Coverity static analysis: Dereference null return value in AbstractDigestMechanism (Elytron)

cipheredPart = wrapCipher.update(toCipher);
// ... cipheredPart may be null
byte[] result = new byte[cipheredPart.length + 6];

// the getTransformationSpec may be null - look at DefaultTransformationMapper
ciph = Cipher.getInstance(trans.getTransformationSpec(SaslMechanismInformation.Names.DIGEST_MD5, cipher).getTransformation());

clearText = unwrapCipher.update(message, offset, len - 6);
// the clearText may be null in clearText.length
System.arraycopy(clearText, clearText.length - 10, hmac, 0, 10);