* Defaults to the project directory.
     * If null, the directory containing the output file will be used.
     */
    public Path getContentPath() {
        return contentPath;
    }

    public void setContentPath(Path contentPath) {
        this.contentPath = contentPath;
    }

    /**
     * The directories containing the production sources.
     * Must not be null.
     */
    public Set<Path> getSourceFolders() {