null when using HttpSolrServer

[sh]

Good day,

I recently moved to solrj 3.6.1. As the CommonsHttpSolrServer class is deprecated in that version I 
migrated to HttpSolrServer. But now tika does not generate the stream_size field correctly, it is 
saying in the result response for an arbitrary jpeg file <str 
name="stream_size">null</str>. Is there any known way to fix that?
The extract handler is defined as:
  
  solrconfig.xml

  <requestHandler name="/update/extract" 
class="solr.extraction.ExtractingRequestHandler">
    <lst name="defaults">
      <str name="lowernames">true</str>
      <str name="fmap.owner">file_owner</str>
      <str name="fmap.path">file_path</str>
    </lst>
  </requestHandler>

 the field in schema.xml looks like that:

 <field name="stream_size" type="string" indexed="true" stored="true" 
multiValued="false" />

Kind regards,

Silvio