Description
SubcollectionIndexingFilter.java is looking for the following variable in nutch-default.xml (at line 56).:
fieldName = conf.get("subcollection.default.fieldname", "subcollection");
nutch-default.xml lists the following:
<property>
<name>subcollection.default.field</name>
<value>subcollection</value>
<description>
The default field name for the subcollections.
</description>
</property>
The field name for nutch-default.xml should be changed from subcollection.default.field to subcollection.default.fieldname.