src/main/java/org/codehaus/plexus/archiver/util/ResourceUtils.java
public static boolean isUptodate( long sourceDate, long destinationDate )
    {
        if ( sourceDate == PlexusIoResource.UNKNOWN_MODIFICATION_DATE )
        {
            return false;
        }

        if ( destinationDate == 0 )
        {
            return false;
        }

        return destinationDate > sourceDate;
    }
public static boolean isUptodate( long sourceDate, long destinationDate )
    {
        if ( sourceDate == PlexusIoResource.UNKNOWN_MODIFICATION_DATE )
        {
            return false;
        }

        if ( destinationDate == 0 )
        {
            return false;
        }

        return destinationDate > sourceDate;
    }
Queries, whether the given source is up-to-date relative to
the given modification date.