Harvest Project and error raised like: Unable to read plugin file % jdeveloper\harvester\plugins\biz.introspector

Solution: Lookup OER repository installation directory <OER_HOME>/core/tools/solutions/*-OER-Harvester-Solution-Pack.zip
Login to OER and navigate: Admin -> Import/Export -> Import / Export Client -> Applet started -> Import -> Select file and press "Next"..
Run "Harvest Project" in jDeveloper again.