return newInstance( getVersion(), copyProperties( properties ), getFile() );
    }

    public String getProperty( String key, String defaultValue )
    {
        String value = getProperties().get( key );
        return ( value != null ) ? value : defaultValue;
    }

    /**
     * Copies the specified artifact properties. This utility method should be used when creating new artifact instances
     * with caller-supplied properties.
     * 
     * @param properties The properties to copy, may be {@code null}.
     * @return The copied and read-only properties, never {@code null}.
     */
    protected static Map<String, String> copyProperties( Map<String, String> properties )
    {
        if ( properties != null && !properties.isEmpty() )
        {
            return Collections.unmodifiableMap( new HashMap<String, String>( properties ) );
        }
        else
        {
            return Collections.emptyMap();
        }
    }

    @Override
    public String toString()
    {
        StringBuilder buffer = new StringBuilder( 128 );