如果附加字段的值没有改变，那么您可以使用Nutch的索引静态插件。它允许您添加多个字段及其内容。首先需要在nutch-site.xml中启用它。然后添加如下所示的字段列表：

<property>
 <name>index.static</name>
 <value>indexed_by:solr,crawled_by:nutch-1.8,crawl_name:nutch</value>
 <description>
  Used by plugin index-static to adds fields with static data at indexing time. 
   You can specify a comma-separated list of fieldname:fieldcontent per Nutch job.
  Each fieldcontent can have multiple values separated by space, e.g.,
   field1:value1.1 value1.2 value1.3,field2:value2.1 value2.2 ...
   It can be useful when collections can't be created by URL patterns, 
  like in subcollection, but on a job-basis.
  </description>
</property>

如果这些字段的值不是静态的，并且独立于索引文档，那么您将需要编写一个IndexingFilter插件来完成此操作。看看索引静态插件，了解如何实现您的插件。