private void assertValidFields ()
    {
        if (_name == null) throw new IllegalArgumentException("The PackageName cannot be null.");
        if (_version == null) throw new IllegalArgumentException("The PackageVersion cannot be null.");
        if (_section == null) throw new IllegalArgumentException("The PackageSection cannot be null.");
        if (_priority == null) throw new IllegalArgumentException("The PackagePriority cannot be null.");
        if (_architecture == null) throw new IllegalArgumentException("The PackageArchitecture cannot be null.");
        if (_maintainer == null) throw new IllegalArgumentException("The PackageMaintainer cannot be null.");
        if (_description == null) throw new IllegalArgumentException("The PackageDescription cannot be null.");
    }