Out-of-the-box AEM / Sling instances do not index [nt:file] documents with text/plain mime type. I've created a custom Lucene index with a Tika configuration node like the one reported below (I tried different class, like TextAndCSVParser; something seems to be wrong. I can survive without full-text search on text/plain files but it's a matter of principle. Any ideas for solving this problem?
<properties>
<parsers>
<parser class="org.apache.tika.parser.defaultParser">
<mime>text/plain</mime>
</parser>
</parsers>
</properties>