For general documentation purposes, I learned that to activate the
language identification plugin, you need to add it to nutch-site.xml in
the plugin.includes property, and most importantly, it requires a dash
in the name: not languageidentifier (as I first tried) but
language-identifier (see below).
<property>
<name>plugin.includes</name>
<value>language-identifier|protocol-http|urlfilter-(regex)|parse-(text|html|js|tika)|index-(basic|anchor)|query-(basic|site|url)|response-(json|xml)|summary-basic|scoring-opic|urlnormalizer-(pass|regex|basic)</value>
<description>...
</description>
</property>
