title: Enabling solr highlighting on field
body: <p>I am trying to enable solr highlighting.  It works on certain fields but doesnt on others.</p>
  <p>The solr documentation says something like   <strong>A '*' can be used to match field globs, such as
  'text_*' or even '*' to highlight on all fields where
  highlighting is possible.</strong></p>
  <p>I would like to know what decides whether a field is one where highlighting is possible</p>