Minor Description
For some reason the language identifier plugin sometimes sets an empty value for the lang field. It is confirmed to occur in 1.2 when parsing a scanned PDF file which cannot be OCR'd to proper text, resulting in an empty content field. Anyway, whether it's a problem with the parser or not, the plugin itself should not add an empty value because the content field can always be empty. The plugin already checks for a null value and then sets the lang field to `unknown`, which is fine. But when the lang string is empty, it should also be set to `unknown`.
This might break clients that have conditional logic on the empty value, but not on the `unknown` value because it may never have occurred in their set up and therefore they might not have added `unknown` to their logic. However, it might seem a little bit overkill to put this proposal behind a configuration option and let Nutch by default continue to behave as it currently does. Any thoughts on this one?
Here's the troublesome URL : http://www.nrc.nl/redactie/binnenland/memo_buza_irak.pdf that returns an empty content field and an empty lang string in 1.2 and presumably in trunk and other versions as well.