private String defaultType() {
        File toSign = getToSign();
        SignatureType signatureType = getSignatureType();
        return toSign != null && signatureType != null
            ? signatureType.combinedExtension(toSign)
            : null;
    }

    public void setClassifier(String classifier) {
        this.classifier = classifier;
    }

    /**
     * The classifier of the signature artifact.